diff --git a/application/Espo/Core/Entities/Person.php b/application/Espo/Core/Entities/Person.php
index ad24b58416..6ab165a5e4 100644
--- a/application/Espo/Core/Entities/Person.php
+++ b/application/Espo/Core/Entities/Person.php
@@ -36,6 +36,7 @@ use Espo\Core\ORM\Entity;
 use Espo\Core\ORM\Helper;
 
 use Espo\ORM\EntityManager;
+use Espo\ORM\Relation\Relations;
 use Espo\ORM\Value\ValueAccessorFactory;
 
 class Person extends Entity
@@ -47,9 +48,16 @@ class Person extends Entity
         array $defs,
         EntityManager $entityManager,
         Helper $helper,
-        ?ValueAccessorFactory $valueAccessorFactory = null
+        ?ValueAccessorFactory $valueAccessorFactory = null,
+        ?Relations $relations = null,
     ) {
-        parent::__construct($entityType, $defs, $entityManager, $valueAccessorFactory);
+        parent::__construct(
+            $entityType,
+            $defs,
+            $entityManager,
+            $valueAccessorFactory,
+            $relations
+        );
 
         $this->helper = $helper;
     }
diff --git a/application/Espo/Core/ORM/Repositories/RDB.php b/application/Espo/Core/ORM/Repositories/RDB.php
index 84bb9568e9..1fc38a71b2 100644
--- a/application/Espo/Core/ORM/Repositories/RDB.php
+++ b/application/Espo/Core/ORM/Repositories/RDB.php
@@ -37,6 +37,7 @@ use Espo\Core\HookManager;
 use Espo\Core\Utils\Id\RecordIdGenerator;
 use Espo\Core\Utils\Metadata;
 use Espo\Core\Utils\SystemUser;
+use Espo\ORM\Relation\RelationsMap;
 
 /**
  * @deprecated As of v6.0. Not to be extended. Extend Espo\Core\Repositories\Database, or better
@@ -97,7 +98,8 @@ class RDB extends \Espo\Core\Repositories\Database implements Injectable /** @ph
         HookManager $hookManager,
         ApplicationState $applicationState,
         RecordIdGenerator $recordIdGenerator,
-        SystemUser $systemUser
+        SystemUser $systemUser,
+        ?RelationsMap $relationsMap,
     ) {
         parent::__construct(
             $entityType,
@@ -107,7 +109,8 @@ class RDB extends \Espo\Core\Repositories\Database implements Injectable /** @ph
             $hookManager,
             $applicationState,
             $recordIdGenerator,
-            $systemUser
+            $systemUser,
+            $relationsMap
         );
 
         $this->init();
diff --git a/application/Espo/Core/Repositories/Database.php b/application/Espo/Core/Repositories/Database.php
index a9cde87a1b..b840119585 100644
--- a/application/Espo/Core/Repositories/Database.php
+++ b/application/Espo/Core/Repositories/Database.php
@@ -33,6 +33,7 @@ use Espo\Core\ORM\Repository\Option\SaveOption;
 use Espo\Core\Utils\SystemUser;
 use Espo\ORM\BaseEntity;
 use Espo\ORM\Entity;
+use Espo\ORM\Relation\RelationsMap;
 use Espo\ORM\Repository\RDBRepository;
 use Espo\Core\ORM\EntityFactory;
 use Espo\Core\ORM\EntityManager;
@@ -84,7 +85,8 @@ class Database extends RDBRepository
         HookManager $hookManager,
         ApplicationState $applicationState,
         RecordIdGenerator $recordIdGenerator,
-        private SystemUser $systemUser
+        private SystemUser $systemUser,
+        ?RelationsMap $relationsMap,
     ) {
         $this->metadata = $metadata;
         $this->hookManager = $hookManager;
@@ -99,7 +101,7 @@ class Database extends RDBRepository
             $hookMediator = new HookMediator($hookManager);
         }
 
-        parent::__construct($entityType, $entityManager, $entityFactory, $hookMediator);
+        parent::__construct($entityType, $entityManager, $entityFactory, $hookMediator, $relationsMap);
     }
 
     /**
diff --git a/application/Espo/Modules/Crm/Entities/Call.php b/application/Espo/Modules/Crm/Entities/Call.php
index dddc021caf..179853ee2d 100644
--- a/application/Espo/Modules/Crm/Entities/Call.php
+++ b/application/Espo/Modules/Crm/Entities/Call.php
@@ -32,6 +32,7 @@ namespace Espo\Modules\Crm\Entities;
 use Espo\Core\Field\DateTime;
 use Espo\Core\Field\Link;
 use Espo\Core\Field\LinkMultiple;
+use Espo\Core\Field\LinkParent;
 use Espo\Core\ORM\Entity;
 
 class Call extends Entity
@@ -126,4 +127,17 @@ class Call extends Entity
         /** @var LinkMultiple */
         return $this->getValueObject('leads');
     }
+
+    public function setParent(Entity|LinkParent|null $parent): self
+    {
+        if ($parent instanceof LinkParent) {
+            $this->setValueObject('parent', $parent);
+
+            return $this;
+        }
+
+        $this->relations->set('parent', $parent);
+
+        return $this;
+    }
 }
diff --git a/application/Espo/Modules/Crm/Entities/Lead.php b/application/Espo/Modules/Crm/Entities/Lead.php
index 410a3c04ed..5e89b76239 100644
--- a/application/Espo/Modules/Crm/Entities/Lead.php
+++ b/application/Espo/Modules/Crm/Entities/Lead.php
@@ -143,4 +143,11 @@ class Lead extends \Espo\Core\Entities\Person
 
         return $this;
     }
+
+    public function setCreatedAccount(Account|null $createdAccount): self
+    {
+        $this->relations->set('createdAccount', $createdAccount);
+
+        return $this;
+    }
 }
diff --git a/application/Espo/Modules/Crm/Entities/Meeting.php b/application/Espo/Modules/Crm/Entities/Meeting.php
index ac78a1d867..2a02f6b4e5 100644
--- a/application/Espo/Modules/Crm/Entities/Meeting.php
+++ b/application/Espo/Modules/Crm/Entities/Meeting.php
@@ -32,6 +32,7 @@ namespace Espo\Modules\Crm\Entities;
 use Espo\Core\Field\DateTimeOptional;
 use Espo\Core\Field\Link;
 use Espo\Core\Field\LinkMultiple;
+use Espo\Core\Field\LinkParent;
 use Espo\Core\ORM\Entity;
 
 class Meeting extends Entity
@@ -131,4 +132,17 @@ class Meeting extends Entity
         /** @var LinkMultiple */
         return $this->getValueObject('leads');
     }
+
+    public function setParent(Entity|LinkParent|null $parent): self
+    {
+        if ($parent instanceof LinkParent) {
+            $this->setValueObject('parent', $parent);
+
+            return $this;
+        }
+
+        $this->relations->set('parent', $parent);
+
+        return $this;
+    }
 }
diff --git a/application/Espo/Modules/Crm/Entities/Opportunity.php b/application/Espo/Modules/Crm/Entities/Opportunity.php
index 686aa10ee2..f2fac77072 100644
--- a/application/Espo/Modules/Crm/Entities/Opportunity.php
+++ b/application/Espo/Modules/Crm/Entities/Opportunity.php
@@ -137,4 +137,17 @@ class Opportunity extends Entity
         /** @var LinkMultiple */
         return $this->getValueObject('teams');
     }
+
+    public function setAccount(Account|Link|null $account): self
+    {
+        if ($account instanceof Link) {
+            $this->setValueObject('account', $account);
+
+            return $this;
+        }
+
+        $this->relations->set('account', $account);
+
+        return $this;
+    }
 }
diff --git a/application/Espo/Modules/Crm/Entities/Task.php b/application/Espo/Modules/Crm/Entities/Task.php
index 2c67e3e302..faf6af7c6e 100644
--- a/application/Espo/Modules/Crm/Entities/Task.php
+++ b/application/Espo/Modules/Crm/Entities/Task.php
@@ -32,6 +32,7 @@ namespace Espo\Modules\Crm\Entities;
 use Espo\Core\Field\DateTimeOptional;
 use Espo\Core\Field\Link;
 use Espo\Core\Field\LinkMultiple;
+use Espo\Core\Field\LinkParent;
 use Espo\Core\ORM\Entity;
 
 class Task extends Entity
@@ -91,4 +92,17 @@ class Task extends Entity
         /** @var string[] */
         return $this->getLinkMultipleIdList('attachments');
     }
+
+    public function setParent(Entity|LinkParent|null $parent): self
+    {
+        if ($parent instanceof LinkParent) {
+            $this->setValueObject('parent', $parent);
+
+            return $this;
+        }
+
+        $this->relations->set('parent', $parent);
+
+        return $this;
+    }
 }
diff --git a/tests/integration/Espo/ORM/RelationsTest.php b/tests/integration/Espo/ORM/RelationsTest.php
index cb92d3207f..d729915051 100644
--- a/tests/integration/Espo/ORM/RelationsTest.php
+++ b/tests/integration/Espo/ORM/RelationsTest.php
@@ -29,9 +29,12 @@
 
 namespace tests\integration\Espo\ORM;
 
+use Espo\Modules\Crm\Entities\Lead;
+use Espo\Modules\Crm\Entities\Task;
 use Espo\ORM\EntityCollection;
 use Espo\Modules\Crm\Entities\Account;
 use Espo\Modules\Crm\Entities\Opportunity;
+use Espo\ORM\Repository\Option\SaveOption;
 use tests\integration\Core\BaseTestCase;
 use tests\integration\testClasses\Entities\Account as AccountExtended;
 use tests\integration\testClasses\Entities\Opportunity as OpportunityExtended;
@@ -113,4 +116,80 @@ class RelationsTest extends BaseTestCase
 
         $this->assertCount(2, $items);
     }
+
+    public function testSet(): void
+    {
+        $metadata = $this->getMetadata();
+        $metadata->set('entityDefs', Account::ENTITY_TYPE, [
+            'entityClassName' => AccountExtended::class,
+        ]);
+        $metadata->save();
+
+        $this->reCreateApplication();
+
+        $em = $this->getEntityManager();
+
+        /** @var Account $account */
+        $account = $em->createEntity(Account::ENTITY_TYPE);
+
+        // belongsTo
+
+        $opp = $em->getRDBRepositoryByClass(Opportunity::class)->getNew();
+        $opp->setAccount($account);
+        $em->saveEntity($opp, [SaveOption::SKIP_ALL => true]);
+        $em->refreshEntity($opp);
+
+        $this->assertEquals($account->getId(), $opp->getAccount()->getId());
+
+        $opp->setAccount(null);
+        $em->saveEntity($opp, [SaveOption::SKIP_ALL => true]);
+        $em->refreshEntity($opp);
+
+        $this->assertNull($opp->getAccount());
+
+        // belongsToParent
+
+        $task = $em->getRDBRepositoryByClass(Task::class)->getNew();
+        $task->setParent($account);
+        $em->saveEntity($task, [SaveOption::SKIP_ALL => true]);
+        $em->refreshEntity($task);
+
+        $this->assertEquals($account->getId(), $task->get('parentId'));
+        $this->assertEquals($account->getEntityType(), $task->get('parentType'));
+
+        $task = $em->getRDBRepositoryByClass(Task::class)->getNew();
+        $task->setParent(null);
+        $em->saveEntity($task, [SaveOption::SKIP_ALL => true]);
+        $em->refreshEntity($task);
+
+        $this->assertNull($task->get('parentId'));
+        $this->assertNull($task->get('parentType'));
+
+        // belongsTo hasOne
+
+        $lead1 = $em->getRDBRepositoryByClass(Lead::class)->getNew();
+        $lead1->setCreatedAccount($account);
+        $em->saveEntity($lead1, [SaveOption::SKIP_ALL => true]);
+        $em->refreshEntity($lead1);
+
+        $this->assertEquals($account->getId(), $lead1->get('createdAccountId'));
+
+        $lead2 = $em->getRDBRepositoryByClass(Lead::class)->getNew();
+        $lead2->setCreatedAccount($account);
+        $em->saveEntity($lead2, [SaveOption::SKIP_ALL => true]);
+        $em->refreshEntity($lead2);
+
+        $this->assertEquals($account->getId(), $lead2->get('createdAccountId'));
+
+        $em->refreshEntity($lead1);
+
+        $this->assertEquals(null, $lead1->get('createdAccountId'));
+
+        $lead2->setCreatedAccount(null);
+        $em->saveEntity($lead2);
+
+        // hasOne
+
+
+    }
 }
diff --git a/tests/integration/testClasses/Entities/Account.php b/tests/integration/testClasses/Entities/Account.php
index 16b7561f4c..b792fe328b 100644
--- a/tests/integration/testClasses/Entities/Account.php
+++ b/tests/integration/testClasses/Entities/Account.php
@@ -29,6 +29,7 @@
 
 namespace tests\integration\testClasses\Entities;
 
+use Espo\Modules\Crm\Entities\Lead;
 use Espo\ORM\EntityCollection;
 
 class Account extends \Espo\Modules\Crm\Entities\Account
@@ -37,4 +38,9 @@ class Account extends \Espo\Modules\Crm\Entities\Account
     {
         return $this->relations->getMany('opportunities');
     }
+
+    public function setRelatedOriginalLead(?Lead $lead): void
+    {
+        $this->relations->set('originalLead', $lead);
+    }
 }