diff --git a/src/Command/KimaiImporterCommand.php b/src/Command/KimaiImporterCommand.php
index b0187c4e..73a57bcb 100644
--- a/src/Command/KimaiImporterCommand.php
+++ b/src/Command/KimaiImporterCommand.php
@@ -763,7 +763,6 @@ class KimaiImporterCommand extends Command
         array $rates,
         ?Project $project
     ) {
-
         $activityId = $oldActivity['activityID'];
         $projectId = null !== $project ? $project->getId() : null;
 
diff --git a/src/Controller/Admin/ActivityController.php b/src/Controller/Admin/ActivityController.php
index ca933d1d..d21c1323 100644
--- a/src/Controller/Admin/ActivityController.php
+++ b/src/Controller/Admin/ActivityController.php
@@ -13,7 +13,10 @@ use App\Controller\AbstractController;
 use App\Entity\Activity;
 use App\Form\ActivityEditForm;
 use App\Form\Toolbar\ActivityToolbarForm;
+use App\Form\Type\ActivityType;
+use App\Repository\ActivityRepository;
 use App\Repository\Query\ActivityQuery;
+use Doctrine\ORM\ORMException;
 use Pagerfanta\Pagerfanta;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Cache;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Security;
@@ -105,6 +108,22 @@ class ActivityController extends AbstractController
         $stats = $this->getRepository()->getActivityStatistics($activity);
 
         $deleteForm = $this->createFormBuilder()
+            ->add('activity', ActivityType::class, [
+                'label' => 'label.activity',
+                'query_builder' => function (ActivityRepository $repo) use ($activity) {
+                    $query = new ActivityQuery();
+                    $query
+                        ->setResultType(ActivityQuery::RESULT_TYPE_QUERYBUILDER)
+                        ->setProject($activity->getProject())
+                        ->setOrderGlobalsFirst(true)
+                        ->addIgnoredEntity($activity)
+                        ->setGlobalsOnly(null === $activity->getProject())
+                    ;
+
+                    return $repo->findByQuery($query);
+                },
+                'required' => false,
+            ])
             ->setAction($this->generateUrl('admin_activity_delete', ['id' => $activity->getId()]))
             ->setMethod('POST')
             ->getForm();
@@ -112,11 +131,12 @@ class ActivityController extends AbstractController
         $deleteForm->handleRequest($request);
 
         if (0 == $stats->getRecordAmount() || ($deleteForm->isSubmitted() && $deleteForm->isValid())) {
-            $entityManager = $this->getDoctrine()->getManager();
-            $entityManager->remove($activity);
-            $entityManager->flush();
-
-            $this->flashSuccess('action.delete.success');
+            try {
+                $this->getRepository()->deleteActivity($activity, $deleteForm->get('activity')->getData());
+                $this->flashSuccess('action.delete.success');
+            } catch (ORMException $ex) {
+                $this->flashError('action.delete.error');
+            }
 
             return $this->redirectToRoute('admin_activity');
         }
diff --git a/src/Controller/Admin/CustomerController.php b/src/Controller/Admin/CustomerController.php
index c667f097..7774a896 100644
--- a/src/Controller/Admin/CustomerController.php
+++ b/src/Controller/Admin/CustomerController.php
@@ -13,7 +13,10 @@ use App\Controller\AbstractController;
 use App\Entity\Customer;
 use App\Form\CustomerEditForm;
 use App\Form\Toolbar\CustomerToolbarForm;
+use App\Form\Type\CustomerType;
+use App\Repository\CustomerRepository;
 use App\Repository\Query\CustomerQuery;
+use Doctrine\ORM\ORMException;
 use Pagerfanta\Pagerfanta;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Security;
 use Symfony\Component\HttpFoundation\Request;
@@ -140,6 +143,18 @@ class CustomerController extends AbstractController
         $stats = $this->getRepository()->getCustomerStatistics($customer);
 
         $deleteForm = $this->createFormBuilder()
+            ->add('customer', CustomerType::class, [
+                'label' => 'label.customer',
+                'query_builder' => function (CustomerRepository $repo) use ($customer) {
+                    $query = new CustomerQuery();
+                    $query
+                        ->setResultType(CustomerQuery::RESULT_TYPE_QUERYBUILDER)
+                        ->addIgnoredEntity($customer);
+
+                    return $repo->findByQuery($query);
+                },
+                'required' => false,
+            ])
             ->setAction($this->generateUrl('admin_customer_delete', ['id' => $customer->getId()]))
             ->setMethod('POST')
             ->getForm();
@@ -147,11 +162,12 @@ class CustomerController extends AbstractController
         $deleteForm->handleRequest($request);
 
         if (0 == $stats->getRecordAmount() || ($deleteForm->isSubmitted() && $deleteForm->isValid())) {
-            $entityManager = $this->getDoctrine()->getManager();
-            $entityManager->remove($customer);
-            $entityManager->flush();
-
-            $this->flashSuccess('action.delete.success');
+            try {
+                $this->getRepository()->deleteCustomer($customer, $deleteForm->get('customer')->getData());
+                $this->flashSuccess('action.delete.success');
+            } catch (ORMException $ex) {
+                $this->flashError('action.delete.error');
+            }
 
             return $this->redirectToRoute('admin_customer');
         }
diff --git a/src/Controller/Admin/ProjectController.php b/src/Controller/Admin/ProjectController.php
index cf3948e4..ccfb6824 100644
--- a/src/Controller/Admin/ProjectController.php
+++ b/src/Controller/Admin/ProjectController.php
@@ -14,7 +14,10 @@ use App\Entity\Customer;
 use App\Entity\Project;
 use App\Form\ProjectEditForm;
 use App\Form\Toolbar\ProjectToolbarForm;
+use App\Form\Type\ProjectType;
+use App\Repository\ProjectRepository;
 use App\Repository\Query\ProjectQuery;
+use Doctrine\ORM\ORMException;
 use Pagerfanta\Pagerfanta;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Cache;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Security;
@@ -99,6 +102,19 @@ class ProjectController extends AbstractController
         $stats = $this->getRepository()->getProjectStatistics($project);
 
         $deleteForm = $this->createFormBuilder()
+            ->add('project', ProjectType::class, [
+                'label' => 'label.project',
+                'query_builder' => function (ProjectRepository $repo) use ($project) {
+                    $query = new ProjectQuery();
+                    $query
+                        ->setResultType(ProjectQuery::RESULT_TYPE_QUERYBUILDER)
+                        ->setCustomer($project->getCustomer())
+                        ->addIgnoredEntity($project);
+
+                    return $repo->findByQuery($query);
+                },
+                'required' => false,
+            ])
             ->setAction($this->generateUrl('admin_project_delete', ['id' => $project->getId()]))
             ->setMethod('POST')
             ->getForm();
@@ -106,11 +122,12 @@ class ProjectController extends AbstractController
         $deleteForm->handleRequest($request);
 
         if (0 == $stats->getRecordAmount() || ($deleteForm->isSubmitted() && $deleteForm->isValid())) {
-            $entityManager = $this->getDoctrine()->getManager();
-            $entityManager->remove($project);
-            $entityManager->flush();
-
-            $this->flashSuccess('action.delete.success');
+            try {
+                $this->getRepository()->deleteProject($project, $deleteForm->get('project')->getData());
+                $this->flashSuccess('action.delete.success');
+            } catch (ORMException $ex) {
+                $this->flashError('action.delete.error');
+            }
 
             return $this->redirectToRoute('admin_project');
         }
diff --git a/src/Repository/ActivityRepository.php b/src/Repository/ActivityRepository.php
index 684007b5..523f0135 100644
--- a/src/Repository/ActivityRepository.php
+++ b/src/Repository/ActivityRepository.php
@@ -15,6 +15,7 @@ use App\Entity\Timesheet;
 use App\Entity\User;
 use App\Model\ActivityStatistic;
 use App\Repository\Query\ActivityQuery;
+use Doctrine\ORM\ORMException;
 use Doctrine\ORM\Query;
 use Doctrine\ORM\QueryBuilder;
 use Pagerfanta\Pagerfanta;
@@ -183,6 +184,11 @@ class ActivityRepository extends AbstractRepository
             $qb->setParameter('customer', $query->getCustomer());
         }
 
+        if (!empty($query->getIgnoredEntities())) {
+            $qb->andWhere('a.id NOT IN(:ignored)');
+            $qb->setParameter('ignored', $query->getIgnoredEntities());
+        }
+
         $or = $qb->expr()->orX();
 
         // this must always be the last part before the or
@@ -204,4 +210,38 @@ class ActivityRepository extends AbstractRepository
 
         return $this->getBaseQueryResult($qb, $query);
     }
+
+    /**
+     * @param Activity $delete
+     * @param Activity|null $replace
+     * @throws \Doctrine\ORM\ORMException
+     * @throws \Doctrine\ORM\OptimisticLockException
+     */
+    public function deleteActivity(Activity $delete, ?Activity $replace = null)
+    {
+        $em = $this->getEntityManager();
+        $em->beginTransaction();
+
+        try {
+            if (null !== $replace) {
+                $qb = $em->createQueryBuilder();
+                $query = $qb
+                    ->update(Timesheet::class, 't')
+                    ->set('t.activity', ':replace')
+                    ->where('t.activity = :delete')
+                    ->setParameter('delete', $delete)
+                    ->setParameter('replace', $replace)
+                    ->getQuery();
+
+                $result = $query->execute();
+            }
+
+            $em->remove($delete);
+            $em->flush();
+            $em->commit();
+        } catch (ORMException $ex) {
+            $em->rollback();
+            throw $ex;
+        }
+    }
 }
diff --git a/src/Repository/CustomerRepository.php b/src/Repository/CustomerRepository.php
index edff162c..b9c88322 100644
--- a/src/Repository/CustomerRepository.php
+++ b/src/Repository/CustomerRepository.php
@@ -15,6 +15,7 @@ use App\Entity\Project;
 use App\Entity\Timesheet;
 use App\Model\CustomerStatistic;
 use App\Repository\Query\CustomerQuery;
+use Doctrine\ORM\ORMException;
 use Doctrine\ORM\Query;
 use Doctrine\ORM\QueryBuilder;
 use Pagerfanta\Pagerfanta;
@@ -121,6 +122,43 @@ class CustomerRepository extends AbstractRepository
             $qb->andWhere('c.visible = 0');
         }
 
+        if (!empty($query->getIgnoredEntities())) {
+            $qb->andWhere('c.id NOT IN(:ignored)');
+            $qb->setParameter('ignored', $query->getIgnoredEntities());
+        }
+
         return $this->getBaseQueryResult($qb, $query);
     }
+
+    /**
+     * @param Customer $delete
+     * @param Customer|null $replace
+     * @throws \Doctrine\ORM\ORMException
+     */
+    public function deleteCustomer(Customer $delete, ?Customer $replace = null)
+    {
+        $em = $this->getEntityManager();
+        $em->beginTransaction();
+
+        try {
+            if (null !== $replace) {
+                $qb = $em->createQueryBuilder();
+                $qb
+                    ->update(Project::class, 'p')
+                    ->set('p.customer', ':replace')
+                    ->where('p.customer = :delete')
+                    ->setParameter('delete', $delete)
+                    ->setParameter('replace', $replace)
+                    ->getQuery()
+                    ->execute();
+            }
+
+            $em->remove($delete);
+            $em->flush();
+            $em->commit();
+        } catch (ORMException $ex) {
+            $em->rollback();
+            throw $ex;
+        }
+    }
 }
diff --git a/src/Repository/ProjectRepository.php b/src/Repository/ProjectRepository.php
index 96a8184f..9d5a1ae8 100644
--- a/src/Repository/ProjectRepository.php
+++ b/src/Repository/ProjectRepository.php
@@ -15,6 +15,7 @@ use App\Entity\Project;
 use App\Entity\Timesheet;
 use App\Model\ProjectStatistic;
 use App\Repository\Query\ProjectQuery;
+use Doctrine\ORM\ORMException;
 use Doctrine\ORM\Query;
 use Doctrine\ORM\QueryBuilder;
 use Pagerfanta\Pagerfanta;
@@ -131,6 +132,53 @@ class ProjectRepository extends AbstractRepository
                 ->setParameter('customer', $query->getCustomer());
         }
 
+        if (!empty($query->getIgnoredEntities())) {
+            $qb->andWhere('p.id NOT IN(:ignored)');
+            $qb->setParameter('ignored', $query->getIgnoredEntities());
+        }
+
         return $this->getBaseQueryResult($qb, $query);
     }
+
+    /**
+     * @param Project $delete
+     * @param Project|null $replace
+     * @throws \Doctrine\ORM\ORMException
+     */
+    public function deleteProject(Project $delete, ?Project $replace = null)
+    {
+        $em = $this->getEntityManager();
+        $em->beginTransaction();
+
+        try {
+            if (null !== $replace) {
+                $qb = $em->createQueryBuilder();
+                $qb
+                    ->update(Timesheet::class, 't')
+                    ->set('t.project', ':replace')
+                    ->where('t.project = :delete')
+                    ->setParameter('delete', $delete)
+                    ->setParameter('replace', $replace)
+                    ->getQuery()
+                    ->execute();
+
+                $qb = $em->createQueryBuilder();
+                $qb
+                    ->update(Activity::class, 'a')
+                    ->set('a.project', ':replace')
+                    ->where('a.project = :delete')
+                    ->setParameter('delete', $delete)
+                    ->setParameter('replace', $replace)
+                    ->getQuery()
+                    ->execute();
+            }
+
+            $em->remove($delete);
+            $em->flush();
+            $em->commit();
+        } catch (ORMException $ex) {
+            $em->rollback();
+            throw $ex;
+        }
+    }
 }
diff --git a/src/Repository/Query/CustomerQuery.php b/src/Repository/Query/CustomerQuery.php
index a0d120b4..a5a8b73a 100644
--- a/src/Repository/Query/CustomerQuery.php
+++ b/src/Repository/Query/CustomerQuery.php
@@ -9,9 +9,34 @@
 
 namespace App\Repository\Query;
 
+use App\Entity\Customer;
+
 /**
  * Can be used for advanced queries with the: CustomerRepository
  */
 class CustomerQuery extends VisibilityQuery
 {
+    /**
+     * @var array
+     */
+    protected $ignored = [];
+
+    /**
+     * @param Customer|int $customer
+     * @return $this
+     */
+    public function addIgnoredEntity($customer)
+    {
+        $this->ignored[] = $customer;
+
+        return $this;
+    }
+
+    /**
+     * @return array
+     */
+    public function getIgnoredEntities()
+    {
+        return $this->ignored;
+    }
 }
diff --git a/src/Repository/Query/ProjectQuery.php b/src/Repository/Query/ProjectQuery.php
index 9f00b1c0..aec5e0cb 100644
--- a/src/Repository/Query/ProjectQuery.php
+++ b/src/Repository/Query/ProjectQuery.php
@@ -21,6 +21,30 @@ class ProjectQuery extends VisibilityQuery
      */
     protected $customer;
 
+    /**
+     * @var array
+     */
+    protected $ignored = [];
+
+    /**
+     * @param mixed $entity
+     * @return $this
+     */
+    public function addIgnoredEntity($entity)
+    {
+        $this->ignored[] = $entity;
+
+        return $this;
+    }
+
+    /**
+     * @return array
+     */
+    public function getIgnoredEntities()
+    {
+        return $this->ignored;
+    }
+
     /**
      * @return Customer|int
      */
diff --git a/src/Repository/TimesheetRepository.php b/src/Repository/TimesheetRepository.php
index 6e8efa62..b4cf727d 100644
--- a/src/Repository/TimesheetRepository.php
+++ b/src/Repository/TimesheetRepository.php
@@ -291,6 +291,7 @@ class TimesheetRepository extends AbstractRepository
             $qb->andWhere('t.begin >= :begin')
                 ->setParameter('begin', $query->getBegin());
         }
+
         if (null !== $query->getEnd()) {
             $qb->andWhere('t.end <= :end')
                 ->setParameter('end', $query->getEnd());
@@ -299,12 +300,16 @@ class TimesheetRepository extends AbstractRepository
         if (null !== $query->getActivity()) {
             $qb->andWhere('t.activity = :activity')
                 ->setParameter('activity', $query->getActivity());
-        } elseif (null !== $query->getProject()) {
-            $qb->andWhere('t.project = :project')
-                ->setParameter('project', $query->getProject());
-        } elseif (null !== $query->getCustomer()) {
-            $qb->andWhere('p.customer = :customer')
-                ->setParameter('customer', $query->getCustomer());
+        }
+
+        if (null === $query->getActivity() || null === $query->getActivity()->getProject()) {
+            if (null !== $query->getProject()) {
+                $qb->andWhere('t.project = :project')
+                    ->setParameter('project', $query->getProject());
+            } elseif (null !== $query->getCustomer()) {
+                $qb->andWhere('p.customer = :customer')
+                    ->setParameter('customer', $query->getCustomer());
+            }
         }
 
         return $this->getBaseQueryResult($qb, $query);
diff --git a/tests/Controller/Admin/ActivityControllerTest.php b/tests/Controller/Admin/ActivityControllerTest.php
index f9fa4994..d08dcf71 100644
--- a/tests/Controller/Admin/ActivityControllerTest.php
+++ b/tests/Controller/Admin/ActivityControllerTest.php
@@ -9,8 +9,10 @@
 
 namespace App\Tests\Controller\Admin;
 
+use App\Entity\Timesheet;
 use App\Entity\User;
 use App\Tests\Controller\ControllerBaseTest;
+use App\Tests\DataFixtures\ActivityFixtures;
 use App\Tests\DataFixtures\ProjectFixtures;
 use App\Tests\DataFixtures\TimesheetFixtures;
 
@@ -127,6 +129,14 @@ class ActivityControllerTest extends ControllerBaseTest
         $fixture->setAmount(10);
         $this->importFixture($em, $fixture);
 
+        $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        $this->assertEquals(10, count($timesheets));
+
+        /** @var Timesheet $entry */
+        foreach($timesheets as $entry) {
+            $this->assertEquals(1, $entry->getActivity()->getId());
+        }
+
         $this->request($client, '/admin/activity/1/delete');
         $this->assertTrue($client->getResponse()->isSuccessful());
 
@@ -139,6 +149,60 @@ class ActivityControllerTest extends ControllerBaseTest
         $this->assertHasDataTable($client);
         $this->assertHasFlashSuccess($client);
 
+        // SQLIte does not necessarly support onCascade delete, so these timesheet will stay after deletion
+        // $em->clear();
+        // $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        // $this->assertEquals(0, count($timesheets));
+
+        $this->request($client, '/admin/activity/1/edit');
+        $this->assertFalse($client->getResponse()->isSuccessful());
+    }
+
+    public function testDeleteActionWithTimesheetEntriesAndReplacement()
+    {
+        $client = $this->getClientForAuthenticatedUser(User::ROLE_ADMIN);
+
+        $em = $client->getContainer()->get('doctrine.orm.entity_manager');
+        $fixture = new TimesheetFixtures();
+        $fixture->setUser($this->getUserByRole($em, User::ROLE_USER));
+        $fixture->setAmount(10);
+        $this->importFixture($em, $fixture);
+        $fixture = new ActivityFixtures();
+        $fixture->setAmount(1)->setIsGlobal(true)->setIsVisible(true);
+        $this->importFixture($em, $fixture);
+
+        $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        $this->assertEquals(10, count($timesheets));
+
+        /** @var Timesheet $entry */
+        foreach($timesheets as $entry) {
+            $this->assertEquals(1, $entry->getActivity()->getId());
+        }
+
+        $this->request($client, '/admin/activity/1/delete');
+        $this->assertTrue($client->getResponse()->isSuccessful());
+
+        $form = $client->getCrawler()->filter('form[name=form]')->form();
+        $this->assertStringEndsWith($this->createUrl('/admin/activity/1/delete'), $form->getUri());
+        $client->submit($form, [
+            'form' => [
+                'activity' => 2
+            ]
+        ]);
+
+        $this->assertIsRedirect($client, $this->createUrl('/admin/activity/'));
+        $client->followRedirect();
+        $this->assertHasDataTable($client);
+        $this->assertHasFlashSuccess($client);
+
+        $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        $this->assertEquals(10, count($timesheets));
+
+        /** @var Timesheet $entry */
+        foreach($timesheets as $entry) {
+            $this->assertEquals(2, $entry->getActivity()->getId());
+        }
+
         $this->request($client, '/admin/activity/1/edit');
         $this->assertFalse($client->getResponse()->isSuccessful());
     }
diff --git a/tests/Controller/Admin/CustomerControllerTest.php b/tests/Controller/Admin/CustomerControllerTest.php
index ee8010e5..4acac03b 100644
--- a/tests/Controller/Admin/CustomerControllerTest.php
+++ b/tests/Controller/Admin/CustomerControllerTest.php
@@ -9,6 +9,7 @@
 
 namespace App\Tests\Controller\Admin;
 
+use App\Entity\Timesheet;
 use App\Entity\User;
 use App\Tests\Controller\ControllerBaseTest;
 use App\Tests\DataFixtures\CustomerFixtures;
@@ -112,6 +113,14 @@ class CustomerControllerTest extends ControllerBaseTest
         $fixture->setAmount(10);
         $this->importFixture($em, $fixture);
 
+        $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        $this->assertEquals(10, count($timesheets));
+
+        /** @var Timesheet $entry */
+        foreach($timesheets as $entry) {
+            $this->assertEquals(1, $entry->getActivity()->getId());
+        }
+
         $this->request($client, '/admin/customer/1/delete');
         $this->assertTrue($client->getResponse()->isSuccessful());
 
@@ -124,6 +133,60 @@ class CustomerControllerTest extends ControllerBaseTest
         $this->assertHasDataTable($client);
         $this->assertHasFlashSuccess($client);
 
+        // SQLIte does not necessarly support onCascade delete, so these timesheet will stay after deletion
+        // $em->clear();
+        // $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        // $this->assertEquals(0, count($timesheets));
+
+        $this->request($client, '/admin/customer/1/edit');
+        $this->assertFalse($client->getResponse()->isSuccessful());
+    }
+
+    public function testDeleteActionWithTimesheetEntriesAndReplacement()
+    {
+        $client = $this->getClientForAuthenticatedUser(User::ROLE_ADMIN);
+
+        $em = $client->getContainer()->get('doctrine.orm.entity_manager');
+        $fixture = new TimesheetFixtures();
+        $fixture->setUser($this->getUserByRole($em, User::ROLE_USER));
+        $fixture->setAmount(10);
+        $this->importFixture($em, $fixture);
+        $fixture = new CustomerFixtures();
+        $fixture->setAmount(1)->setIsVisible(true);
+        $this->importFixture($em, $fixture);
+
+        $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        $this->assertEquals(10, count($timesheets));
+
+        /** @var Timesheet $entry */
+        foreach($timesheets as $entry) {
+            $this->assertEquals(1, $entry->getProject()->getCustomer()->getId());
+        }
+
+        $this->request($client, '/admin/customer/1/delete');
+        $this->assertTrue($client->getResponse()->isSuccessful());
+
+        $form = $client->getCrawler()->filter('form[name=form]')->form();
+        $this->assertStringEndsWith($this->createUrl('/admin/customer/1/delete'), $form->getUri());
+        $client->submit($form, [
+            'form' => [
+                'customer' => 2
+            ]
+        ]);
+
+        $this->assertIsRedirect($client, $this->createUrl('/admin/customer/'));
+        $client->followRedirect();
+        $this->assertHasDataTable($client);
+        $this->assertHasFlashSuccess($client);
+
+        $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        $this->assertEquals(10, count($timesheets));
+
+        /** @var Timesheet $entry */
+        foreach($timesheets as $entry) {
+            $this->assertEquals(2, $entry->getProject()->getCustomer()->getId());
+        }
+
         $this->request($client, '/admin/customer/1/edit');
         $this->assertFalse($client->getResponse()->isSuccessful());
     }
diff --git a/tests/Controller/Admin/ProjectControllerTest.php b/tests/Controller/Admin/ProjectControllerTest.php
index f065abc5..8c3a17c3 100644
--- a/tests/Controller/Admin/ProjectControllerTest.php
+++ b/tests/Controller/Admin/ProjectControllerTest.php
@@ -9,6 +9,7 @@
 
 namespace App\Tests\Controller\Admin;
 
+use App\Entity\Timesheet;
 use App\Entity\User;
 use App\Tests\Controller\ControllerBaseTest;
 use App\Tests\DataFixtures\CustomerFixtures;
@@ -135,6 +136,14 @@ class ProjectControllerTest extends ControllerBaseTest
         $fixture->setAmount(10);
         $this->importFixture($em, $fixture);
 
+        $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        $this->assertEquals(10, count($timesheets));
+
+        /** @var Timesheet $entry */
+        foreach($timesheets as $entry) {
+            $this->assertEquals(1, $entry->getActivity()->getId());
+        }
+
         $this->request($client, '/admin/project/1/delete');
         $this->assertTrue($client->getResponse()->isSuccessful());
 
@@ -147,6 +156,60 @@ class ProjectControllerTest extends ControllerBaseTest
         $this->assertHasDataTable($client);
         $this->assertHasFlashSuccess($client);
 
+        // SQLIte does not necessarly support onCascade delete, so these timesheet will stay after deletion
+        // $em->clear();
+        // $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        // $this->assertEquals(0, count($timesheets));
+
+        $this->request($client, '/admin/project/1/edit');
+        $this->assertFalse($client->getResponse()->isSuccessful());
+    }
+
+    public function testDeleteActionWithTimesheetEntriesAndReplacement()
+    {
+        $client = $this->getClientForAuthenticatedUser(User::ROLE_ADMIN);
+
+        $em = $client->getContainer()->get('doctrine.orm.entity_manager');
+        $fixture = new TimesheetFixtures();
+        $fixture->setUser($this->getUserByRole($em, User::ROLE_USER));
+        $fixture->setAmount(10);
+        $this->importFixture($em, $fixture);
+        $fixture = new ProjectFixtures();
+        $fixture->setAmount(1)->setIsVisible(true);
+        $this->importFixture($em, $fixture);
+
+        $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        $this->assertEquals(10, count($timesheets));
+
+        /** @var Timesheet $entry */
+        foreach($timesheets as $entry) {
+            $this->assertEquals(1, $entry->getProject()->getId());
+        }
+
+        $this->request($client, '/admin/project/1/delete');
+        $this->assertTrue($client->getResponse()->isSuccessful());
+
+        $form = $client->getCrawler()->filter('form[name=form]')->form();
+        $this->assertStringEndsWith($this->createUrl('/admin/project/1/delete'), $form->getUri());
+        $client->submit($form, [
+            'form' => [
+                'project' => 2
+            ]
+        ]);
+
+        $this->assertIsRedirect($client, $this->createUrl('/admin/project/'));
+        $client->followRedirect();
+        $this->assertHasDataTable($client);
+        $this->assertHasFlashSuccess($client);
+
+        $timesheets = $em->getRepository(Timesheet::class)->findAll();
+        $this->assertEquals(10, count($timesheets));
+
+        /** @var Timesheet $entry */
+        foreach($timesheets as $entry) {
+            $this->assertEquals(2, $entry->getProject()->getId());
+        }
+
         $this->request($client, '/admin/project/1/edit');
         $this->assertFalse($client->getResponse()->isSuccessful());
     }
diff --git a/tests/DataFixtures/ActivityFixtures.php b/tests/DataFixtures/ActivityFixtures.php
index f49884b5..b45a3273 100644
--- a/tests/DataFixtures/ActivityFixtures.php
+++ b/tests/DataFixtures/ActivityFixtures.php
@@ -25,6 +25,14 @@ class ActivityFixtures extends Fixture
      * @var int
      */
     protected $amount = 0;
+    /**
+     * @var bool
+     */
+    protected $isGlobal = false;
+    /**
+     * @var bool
+     */
+    protected $isVisible = null;
 
     /**
      * @return int
@@ -34,6 +42,28 @@ class ActivityFixtures extends Fixture
         return $this->amount;
     }
 
+    /**
+     * @param bool $global
+     * @return $this
+     */
+    public function setIsGlobal(bool $global)
+    {
+        $this->isGlobal = $global;
+
+        return $this;
+    }
+
+    /**
+     * @param bool $visible
+     * @return $this
+     */
+    public function setIsVisible(bool $visible)
+    {
+        $this->isVisible = $visible;
+
+        return $this;
+    }
+
     /**
      * @param int $amount
      * @return ActivityFixtures
@@ -55,10 +85,17 @@ class ActivityFixtures extends Fixture
 
         // random amount of timesheet entries for every user
         for ($i = 0; $i < $this->amount; $i++) {
+            $project = null;
+            if (false === $this->isGlobal) {
+                $project = $projects[array_rand($projects)];
+            }
             $visible = 0 != $i % 3;
+            if (null !== $this->isVisible) {
+                $visible = $this->isVisible;
+            }
             $entity = new Activity();
             $entity
-                ->setProject($projects[array_rand($projects)])
+                ->setProject($project)
                 ->setName($faker->bs . ($visible ? '' : ' (x)'))
                 ->setComment($faker->text)
                 ->setVisible($visible)
diff --git a/tests/DataFixtures/CustomerFixtures.php b/tests/DataFixtures/CustomerFixtures.php
index 090baa80..a594f6c9 100644
--- a/tests/DataFixtures/CustomerFixtures.php
+++ b/tests/DataFixtures/CustomerFixtures.php
@@ -24,6 +24,10 @@ class CustomerFixtures extends Fixture
      * @var int
      */
     protected $amount = 0;
+    /**
+     * @var bool
+     */
+    protected $isVisible = null;
 
     /**
      * @return int
@@ -44,6 +48,17 @@ class CustomerFixtures extends Fixture
         return $this;
     }
 
+    /**
+     * @param bool $visible
+     * @return $this
+     */
+    public function setIsVisible(bool $visible)
+    {
+        $this->isVisible = $visible;
+
+        return $this;
+    }
+
     /**
      * {@inheritdoc}
      */
@@ -53,6 +68,9 @@ class CustomerFixtures extends Fixture
 
         for ($i = 0; $i < $this->amount; $i++) {
             $visible = 0 != $i % 3;
+            if (null !== $this->isVisible) {
+                $visible = $this->isVisible;
+            }
             $entity = new Customer();
             $entity
                 ->setCurrency($faker->currencyCode)
diff --git a/tests/DataFixtures/ProjectFixtures.php b/tests/DataFixtures/ProjectFixtures.php
index a18cbd8c..729a3b27 100644
--- a/tests/DataFixtures/ProjectFixtures.php
+++ b/tests/DataFixtures/ProjectFixtures.php
@@ -25,6 +25,10 @@ class ProjectFixtures extends Fixture
      * @var int
      */
     protected $amount = 0;
+    /**
+     * @var bool
+     */
+    protected $isVisible = null;
 
     /**
      * @return int
@@ -45,6 +49,17 @@ class ProjectFixtures extends Fixture
         return $this;
     }
 
+    /**
+     * @param bool $visible
+     * @return $this
+     */
+    public function setIsVisible(bool $visible)
+    {
+        $this->isVisible = $visible;
+
+        return $this;
+    }
+
     /**
      * {@inheritdoc}
      */
@@ -55,6 +70,9 @@ class ProjectFixtures extends Fixture
 
         for ($i = 0; $i < $this->amount; $i++) {
             $visible = 0 != $i % 3;
+            if (null !== $this->isVisible) {
+                $visible = $this->isVisible;
+            }
             $entity = new Project();
             $entity
                 ->setName($faker->catchPhrase . ($visible ? '' : ' (x)'))
diff --git a/translations/messages.de.xliff b/translations/messages.de.xliff
index 2158316e..1c55a73d 100644
--- a/translations/messages.de.xliff
+++ b/translations/messages.de.xliff
@@ -442,6 +442,7 @@
                     Momentan existieren für das Projekt %project% des Kunden %customer% insgesamt %activities%
                     Tätigkeiten und %records% Zeiteinträge, welche sich auf eine Gesamtdauer von %duration% belaufen.
                     Diese Tätigkeiten und Zeiteinträge werden ebenfalls mit gelöscht!
+                    Alternativ können Sie ein Projekt auswählen, auf das alle existierenden Aktivitäten und Einträge umgebucht werden:
                 </target>
             </trans-unit>
 
@@ -462,6 +463,7 @@
                     Momentan existieren für die Tätigkeit %activity% im Projekt %project% für den Kunden %customer%
                     insgesamt %records% Zeiteinträge, welche sich auf eine Gesamtdauer von %duration% belaufen. Diese
                     Zeiteinträge werden ebenfalls mit gelöscht!
+                    Alternativ können Sie eine Tätigkeit auswählen, auf die alle existierenden Einträge umgebucht werden:
                 </target>
             </trans-unit>
 
@@ -530,6 +532,7 @@
                     Momentan existieren für den Kunden %customer% insgesamt %project% Projekte mit %activity%
                     Tätigkeiten, die sich in %records% Zeiteinträgen auf eine Gesamtdauer von %duration% belaufen. Diese
                     Projekte, Tätigkeiten und Zeiteinträge werden ebenfalls mit gelöscht!
+                    Alternativ können Sie einen Kunden auswählen, auf den alle Daten umgebucht werden:
                 </target>
             </trans-unit>
 
diff --git a/translations/messages.en.xliff b/translations/messages.en.xliff
index 4132190d..ee86ba82 100644
--- a/translations/messages.en.xliff
+++ b/translations/messages.en.xliff
@@ -442,6 +442,7 @@
                     Currently the project %project% for the customer %customer% has %activities%
                     activities and %records% time-records, which count up to a total of %duration%.
                     These activities and time-records will be deleted as well!
+                    Alternatively, you can select a project to which all existing activities and entries are transferred:
                 </target>
             </trans-unit>
 
@@ -462,6 +463,7 @@
                     Currently the activity %activity% in the project %project% for the customer %customer%
                     has %records% time-records, which count up to a total of %duration%.
                     These time-records will be deleted as well!
+                    Alternatively, you can select an activity to which all existing entries are transferred:
                 </target>
             </trans-unit>
 
@@ -530,6 +532,7 @@
                     Currently the customer %customer% has %project% projects with %activity% activities, which count up
                     in %records% time-records to a total of %duration%.
                     These projects, activities and time-records will be deleted as well!
+                    Alternatively, you can select a customer to whom all data is transferred:
                 </target>
             </trans-unit>