diff --git a/application/Espo/Classes/Acl/Email/AssignmentChecker.php b/application/Espo/Classes/Acl/Email/AssignmentChecker.php
index 4d7bfa643a..97894c223d 100644
--- a/application/Espo/Classes/Acl/Email/AssignmentChecker.php
+++ b/application/Espo/Classes/Acl/Email/AssignmentChecker.php
@@ -29,19 +29,30 @@
 
 namespace Espo\Classes\Acl\Email;
 
+use Espo\Core\Acl\AssignmentChecker as AssignmentCheckerInterface;
+use Espo\Entities\Email;
 use Espo\Entities\User;
 use Espo\ORM\Entity;
-use Espo\Core\Acl\DefaultAssignmentChecker;
 
-class AssignmentChecker extends DefaultAssignmentChecker
+/**
+ * @implements AssignmentCheckerInterface<Email>
+ */
+class AssignmentChecker implements AssignmentCheckerInterface
 {
-    protected function isPermittedAssignedUser(User $user, Entity $entity): bool
-    {
-        return true;
-    }
+    public function __construct(
+        private AssignmentCheckerInterface\Helper $helper,
+    ) {}
 
-    protected function isPermittedAssignedUsers(User $user, Entity $entity): bool
+    public function check(User $user, Entity $entity): bool
     {
+        if ($entity->getAssignedUser() && !$this->helper->checkAssignedUser($user, $entity)) {
+            return false;
+        }
+
+        if ($entity->getTeams()->getIdList() !== [] && !$this->helper->checkTeams($user, $entity)) {
+            return false;
+        }
+
         return true;
     }
 }
diff --git a/application/Espo/Core/Acl/AssignmentChecker/Helper.php b/application/Espo/Core/Acl/AssignmentChecker/Helper.php
new file mode 100644
index 0000000000..24f49cb5e4
--- /dev/null
+++ b/application/Espo/Core/Acl/AssignmentChecker/Helper.php
@@ -0,0 +1,339 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM – Open Source CRM application.
+ * Copyright (C) 2014-2024 Yurii Kuznietsov, Taras Machyshyn, Oleksii Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU Affero General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU Affero General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\Core\Acl\AssignmentChecker;
+
+use Espo\Core\Acl\Permission;
+use Espo\Core\Acl\Table;
+use Espo\Core\AclManager;
+use Espo\Core\Name\Field;
+use Espo\Core\ORM\Entity as CoreEntity;
+use Espo\Core\ORM\Type\FieldType;
+use Espo\Core\Utils\Metadata;
+use Espo\Entities\User;
+use Espo\ORM\Defs;
+use Espo\ORM\Entity;
+use Espo\ORM\EntityManager;
+use Espo\ORM\Name\Attribute;
+use Espo\Repositories\User as UserRepository;
+
+class Helper
+{
+    private const ATTR_ASSIGNED_USER_ID = Field::ASSIGNED_USER . 'Id';
+    private const FIELD_TEAMS = Field::TEAMS;
+    private const FIELD_ASSIGNED_USERS = Field::ASSIGNED_USERS;
+    private const FIELD_COLLABORATORS = Field::COLLABORATORS;
+
+    public function __construct(
+        private EntityManager $entityManager,
+        private AclManager $aclManager,
+        private Defs $ormDefs,
+        private Metadata $metadata,
+    ) {}
+
+    public function checkAssignedUser(User $user, Entity $entity): bool
+    {
+        if (!$entity->hasAttribute(self::ATTR_ASSIGNED_USER_ID)) {
+            return true;
+        }
+
+        if ($user->isPortal()) {
+            return !$entity->isAttributeChanged(self::ATTR_ASSIGNED_USER_ID);
+        }
+
+        $assignmentPermission = $this->aclManager->getPermissionLevel($user, Permission::ASSIGNMENT);
+
+        if ($assignmentPermission === Table::LEVEL_ALL) {
+            return true;
+        }
+
+        $toProcess = false;
+
+        if (!$entity->isNew()) {
+            if ($entity->isAttributeChanged(self::ATTR_ASSIGNED_USER_ID)) {
+                $toProcess = true;
+            }
+        } else {
+            $toProcess = true;
+        }
+
+        if (!$toProcess) {
+            return true;
+        }
+
+        $assignedUserId = $entity->get(self::ATTR_ASSIGNED_USER_ID);
+
+        if (!$assignedUserId) {
+            if ($assignmentPermission === Table::LEVEL_NO && !$user->isApi()) {
+                return false;
+            }
+
+            return true;
+        }
+
+        if ($assignmentPermission === Table::LEVEL_NO) {
+            return $user->getId() === $assignedUserId;
+        }
+
+        if ($assignmentPermission === Table::LEVEL_TEAM) {
+            $teamIdList = $user->getTeamIdList();
+
+            return $this->getUserRepository()->checkBelongsToAnyOfTeams($assignedUserId, $teamIdList);
+        }
+
+        return false;
+    }
+
+    public function checkTeams(User $user, Entity $entity): bool
+    {
+        $assignmentPermission = $this->aclManager->getPermissionLevel($user, Permission::ASSIGNMENT);
+
+        if (!in_array($assignmentPermission, [Table::LEVEL_TEAM, Table::LEVEL_NO])) {
+            return true;
+        }
+
+        if (!$entity instanceof CoreEntity) {
+            return true;
+        }
+
+        if (!$entity->hasLinkMultipleField(self::FIELD_TEAMS)) {
+            return true;
+        }
+
+        $teamIdList = $entity->getLinkMultipleIdList(self::FIELD_TEAMS);
+
+        if ($teamIdList === []) {
+            return $this->isPermittedTeamsEmpty($user, $entity);
+        }
+
+        $newIdList = [];
+
+        if (!$entity->isNew()) {
+            $existingIdList = [];
+
+            $teamCollection = $this->entityManager
+                ->getRelation($entity, self::FIELD_TEAMS)
+                ->select(Attribute::ID)
+                ->find();
+
+            foreach ($teamCollection as $team) {
+                $existingIdList[] = $team->getId();
+            }
+
+            foreach ($teamIdList as $id) {
+                if (!in_array($id, $existingIdList)) {
+                    $newIdList[] = $id;
+                }
+            }
+        } else {
+            $newIdList = $teamIdList;
+        }
+
+        if ($newIdList === []) {
+            return true;
+        }
+
+        $userTeamIdList = $user->getLinkMultipleIdList(self::FIELD_TEAMS);
+
+        foreach ($newIdList as $id) {
+            if (!in_array($id, $userTeamIdList)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    public function checkUsers(User $user, Entity $entity, string $field): bool
+    {
+        if (!$entity instanceof CoreEntity) {
+            return true;
+        }
+
+        $idsAttr = $field . 'Ids';
+
+        if (!$entity->hasLinkMultipleField($field)) {
+            return true;
+        }
+
+        if ($user->isPortal()) {
+            if (!$entity->isAttributeChanged($idsAttr)) {
+                return true;
+            }
+
+            return false;
+        }
+
+        $assignmentPermission = $this->aclManager->getPermissionLevel($user, Permission::ASSIGNMENT);
+
+        if ($assignmentPermission === Table::LEVEL_ALL) {
+            if (!$this->hasOnlyInternalUsers($user, $entity, $field)) {
+                return false;
+            }
+
+            return true;
+        }
+
+        $toProcess = $entity->isNew() || $entity->isAttributeChanged($idsAttr);
+
+        if (!$toProcess) {
+            return true;
+        }
+
+        $userIds = $entity->getLinkMultipleIdList($field);
+
+        if ($userIds === []) {
+            if ($assignmentPermission === Table::LEVEL_NO && !$user->isApi()) {
+                return false;
+            }
+
+            return true;
+        }
+
+        if ($assignmentPermission === Table::LEVEL_NO) {
+            return $this->isPermittedUsersLevelNo($user, $entity, $field);
+        }
+
+        if ($assignmentPermission === Table::LEVEL_TEAM) {
+            return $this->isPermittedUsersLevelTeam($user, $entity, $field);
+        }
+
+        return false;
+    }
+
+    private function isPermittedUsersLevelNo(User $user, CoreEntity $entity, string $field): bool
+    {
+        $userIds = $this->getAddedLinkMultipleIds($entity, $field);
+
+        foreach ($userIds as $userId) {
+            if ($user->getId() !== $userId) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private function isPermittedUsersLevelTeam(User $user, CoreEntity $entity, string $field): bool
+    {
+        $teamIds = $user->getLinkMultipleIdList(self::FIELD_TEAMS);
+        $userIds = $this->getAddedLinkMultipleIds($entity, $field);
+
+        foreach ($userIds as $userId) {
+            if (!$this->getUserRepository()->checkBelongsToAnyOfTeams($userId, $teamIds)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private function hasOnlyInternalUsers(User $user, CoreEntity $entity, string $field): bool
+    {
+        $ids = array_diff($this->getAddedLinkMultipleIds($entity, $field), [$user->getId()]);
+        $ids = array_values($ids);
+
+        $count = $this->entityManager
+            ->getRDBRepositoryByClass(User::class)
+            ->where([
+                'type!=' => [
+                    User::TYPE_REGULAR,
+                    User::TYPE_ADMIN,
+                ],
+                Attribute::ID => $ids,
+            ])
+            ->count();
+
+        return $count === 0;
+    }
+
+    /**
+     * @return string[]
+     */
+    private function getAddedLinkMultipleIds(CoreEntity $entity, string $field): array
+    {
+        /** @var string[] $previousIds */
+        $previousIds = $entity->getFetched(self::FIELD_COLLABORATORS . 'Ids') ?? [];
+
+        return array_values(array_diff($entity->getLinkMultipleIdList($field), $previousIds));
+    }
+
+    private function isPermittedTeamsEmpty(User $user, CoreEntity $entity): bool
+    {
+        $assignmentPermission = $this->aclManager->getPermissionLevel($user, Permission::ASSIGNMENT);
+
+        if ($assignmentPermission !== Table::LEVEL_TEAM) {
+            return true;
+        }
+
+        if ($entity->hasLinkMultipleField(self::FIELD_ASSIGNED_USERS)) {
+            $assignedUserIdList = $entity->getLinkMultipleIdList(self::FIELD_ASSIGNED_USERS);
+
+            if ($assignedUserIdList === []) {
+                return false;
+            }
+        } else if ($entity->hasAttribute(self::ATTR_ASSIGNED_USER_ID)) {
+            if (!$entity->get(self::ATTR_ASSIGNED_USER_ID)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    public function hasAssignedUsersField(string $entityType): bool
+    {
+        $entityDefs = $this->ormDefs->getEntity($entityType);
+
+        return
+            $entityDefs->hasField(self::FIELD_ASSIGNED_USERS) &&
+            $entityDefs->getField(self::FIELD_ASSIGNED_USERS)->getType() === FieldType::LINK_MULTIPLE &&
+            $entityDefs->hasRelation(self::FIELD_ASSIGNED_USERS) &&
+            $entityDefs->getRelation(self::FIELD_ASSIGNED_USERS)->getForeignEntityType() === User::ENTITY_TYPE;
+    }
+
+    public function hasCollaboratorsField(string $entityType): bool
+    {
+        if (!$this->metadata->get("scopes.$entityType.collaborators")) {
+            return false;
+        }
+
+        $entityDefs = $this->ormDefs->getEntity($entityType);
+
+        return
+            $entityDefs->tryGetField(self::FIELD_COLLABORATORS)?->getType() === FieldType::LINK_MULTIPLE &&
+            $entityDefs->tryGetRelation(self::FIELD_COLLABORATORS)?->tryGetForeignEntityType() === User::ENTITY_TYPE;
+    }
+
+    private function getUserRepository(): UserRepository
+    {
+        /** @var UserRepository */
+        return $this->entityManager->getRepository(User::ENTITY_TYPE);
+    }
+}
diff --git a/application/Espo/Core/Acl/DefaultAssignmentChecker.php b/application/Espo/Core/Acl/DefaultAssignmentChecker.php
index d7bf408a18..905616cd51 100644
--- a/application/Espo/Core/Acl/DefaultAssignmentChecker.php
+++ b/application/Espo/Core/Acl/DefaultAssignmentChecker.php
@@ -29,17 +29,11 @@
 
 namespace Espo\Core\Acl;
 
+use Espo\Core\Acl\AssignmentChecker\Helper;
 use Espo\Core\Name\Field;
 use Espo\Core\ORM\Entity as CoreEntity;
-use Espo\Core\ORM\Type\FieldType;
-use Espo\Core\Utils\Metadata;
-use Espo\ORM\Name\Attribute;
-use Espo\Repositories\User as UserRepository;
-use Espo\ORM\Defs;
 use Espo\ORM\Entity;
-use Espo\ORM\EntityManager;
 use Espo\Entities\User;
-use Espo\Core\AclManager;
 
 /**
  * @implements AssignmentChecker<CoreEntity>
@@ -47,15 +41,10 @@ use Espo\Core\AclManager;
 class DefaultAssignmentChecker implements AssignmentChecker
 {
     protected const FIELD_ASSIGNED_USERS = Field::ASSIGNED_USERS;
-    protected const FIELD_TEAMS = Field::TEAMS;
-    protected const ATTR_ASSIGNED_USER_ID = 'assignedUserId';
     private const FIELD_COLLABORATORS = Field::COLLABORATORS;
 
     public function __construct(
-        private AclManager $aclManager,
-        private EntityManager $entityManager,
-        private Defs $ormDefs,
-        private Metadata $metadata,
+        private Helper $helper,
     ) {}
 
     public function check(User $user, Entity $entity): bool
@@ -68,14 +57,14 @@ class DefaultAssignmentChecker implements AssignmentChecker
             return false;
         }
 
-        if ($this->hasAssignedUsersField($entity->getEntityType())) {
+        if ($this->helper->hasAssignedUsersField($entity->getEntityType())) {
             if (!$this->isPermittedAssignedUsers($user, $entity)) {
                 return false;
             }
         }
 
-        if ($this->hasCollaboratorsField($entity->getEntityType())) {
-            if (!$this->isPermittedUsers($user, $entity, self::FIELD_COLLABORATORS)) {
+        if ($this->helper->hasCollaboratorsField($entity->getEntityType())) {
+            if (!$this->helper->checkUsers($user, $entity, self::FIELD_COLLABORATORS)) {
                 return false;
             }
         }
@@ -83,182 +72,14 @@ class DefaultAssignmentChecker implements AssignmentChecker
         return true;
     }
 
-    private function hasCollaboratorsField(string $entityType): bool
-    {
-        if (!$this->metadata->get("scopes.$entityType.collaborators")) {
-            return false;
-        }
-
-        $entityDefs = $this->ormDefs->getEntity($entityType);
-
-        return
-            $entityDefs->tryGetField(self::FIELD_COLLABORATORS)?->getType() === FieldType::LINK_MULTIPLE &&
-            $entityDefs->tryGetRelation(self::FIELD_COLLABORATORS)?->tryGetForeignEntityType() === User::ENTITY_TYPE;
-    }
-
-    private function hasAssignedUsersField(string $entityType): bool
-    {
-        $entityDefs = $this->ormDefs->getEntity($entityType);
-
-        return
-            $entityDefs->hasField(self::FIELD_ASSIGNED_USERS) &&
-            $entityDefs->getField(self::FIELD_ASSIGNED_USERS)->getType() === FieldType::LINK_MULTIPLE &&
-            $entityDefs->hasRelation(self::FIELD_ASSIGNED_USERS) &&
-            $entityDefs->getRelation(self::FIELD_ASSIGNED_USERS)->getForeignEntityType() === User::ENTITY_TYPE;
-    }
-
     protected function isPermittedAssignedUser(User $user, Entity $entity): bool
     {
-        if (!$entity->hasAttribute(self::ATTR_ASSIGNED_USER_ID)) {
-            return true;
-        }
-
-        $assignedUserId = $entity->get(self::ATTR_ASSIGNED_USER_ID);
-
-        if ($user->isPortal()) {
-            if (!$entity->isAttributeChanged(self::ATTR_ASSIGNED_USER_ID)) {
-                return true;
-            }
-
-            return false;
-        }
-
-        $assignmentPermission = $this->aclManager->getPermissionLevel($user, Permission::ASSIGNMENT);
-
-        if (
-            $assignmentPermission === Table::LEVEL_YES ||
-            !in_array($assignmentPermission, [Table::LEVEL_TEAM, Table::LEVEL_NO])
-        ) {
-            return true;
-        }
-
-        $toProcess = false;
-
-        if (!$entity->isNew()) {
-            if ($entity->isAttributeChanged(self::ATTR_ASSIGNED_USER_ID)) {
-                $toProcess = true;
-            }
-        } else {
-            $toProcess = true;
-        }
-
-        if (!$toProcess) {
-            return true;
-        }
-
-        if (empty($assignedUserId)) {
-            if ($assignmentPermission === Table::LEVEL_NO && !$user->isApi()) {
-                return false;
-            }
-
-            return true;
-        }
-
-        if ($assignmentPermission === Table::LEVEL_NO) {
-            if ($user->getId() !== $assignedUserId) {
-                return false;
-            }
-        } else if ($assignmentPermission === Table::LEVEL_TEAM) {
-            $teamIdList = $user->getTeamIdList();
-
-            if (
-                !$this->getUserRepository()->checkBelongsToAnyOfTeams($assignedUserId, $teamIdList)
-            ) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    private function getUserRepository(): UserRepository
-    {
-        /** @var UserRepository */
-        return $this->entityManager->getRepository('User');
+        return $this->helper->checkAssignedUser($user, $entity);
     }
 
     protected function isPermittedTeams(User $user, Entity $entity): bool
     {
-        $assignmentPermission = $this->aclManager->getPermissionLevel($user, Permission::ASSIGNMENT);
-
-        if (!in_array($assignmentPermission, [Table::LEVEL_TEAM, Table::LEVEL_NO])) {
-            return true;
-        }
-
-        if (!$entity instanceof CoreEntity) {
-            return true;
-        }
-
-        if (!$entity->hasLinkMultipleField(self::FIELD_TEAMS)) {
-            return true;
-        }
-
-        $teamIdList = $entity->getLinkMultipleIdList(self::FIELD_TEAMS);
-
-        if (empty($teamIdList)) {
-            return $this->isPermittedTeamsEmpty($user, $entity);
-        }
-
-        $newIdList = [];
-
-        if (!$entity->isNew()) {
-            $existingIdList = [];
-
-            $teamCollection = $this->entityManager
-                ->getRDBRepository($entity->getEntityType())
-                ->getRelation($entity, self::FIELD_TEAMS)
-                ->select(Attribute::ID)
-                ->find();
-
-            foreach ($teamCollection as $team) {
-                $existingIdList[] = $team->getId();
-            }
-
-            foreach ($teamIdList as $id) {
-                if (!in_array($id, $existingIdList)) {
-                    $newIdList[] = $id;
-                }
-            }
-        } else {
-            $newIdList = $teamIdList;
-        }
-
-        if (empty($newIdList)) {
-            return true;
-        }
-
-        $userTeamIdList = $user->getLinkMultipleIdList(self::FIELD_TEAMS);
-
-        foreach ($newIdList as $id) {
-            if (!in_array($id, $userTeamIdList)) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    private function isPermittedTeamsEmpty(User $user, CoreEntity $entity): bool
-    {
-        $assignmentPermission = $this->aclManager->getPermissionLevel($user, Permission::ASSIGNMENT);
-
-        if ($assignmentPermission !== Table::LEVEL_TEAM) {
-            return true;
-        }
-
-        if ($entity->hasLinkMultipleField(self::FIELD_ASSIGNED_USERS)) {
-            $assignedUserIdList = $entity->getLinkMultipleIdList(self::FIELD_ASSIGNED_USERS);
-
-            if (empty($assignedUserIdList)) {
-                return false;
-            }
-        } else if ($entity->hasAttribute(self::ATTR_ASSIGNED_USER_ID)) {
-            if (!$entity->get(self::ATTR_ASSIGNED_USER_ID)) {
-                return false;
-            }
-        }
-
-        return true;
+        return $this->helper->checkTeams($user, $entity);
     }
 
     /**
@@ -266,120 +87,6 @@ class DefaultAssignmentChecker implements AssignmentChecker
      */
     protected function isPermittedAssignedUsers(User $user, Entity $entity): bool
     {
-        return $this->isPermittedUsers($user, $entity, self::FIELD_ASSIGNED_USERS);
-    }
-
-    private function isPermittedUsers(User $user, Entity $entity, string $field): bool
-    {
-        if (!$entity instanceof CoreEntity) {
-            return true;
-        }
-
-        $idsAttr = $field . 'Ids';
-
-        if (!$entity->hasLinkMultipleField($field)) {
-            return true;
-        }
-
-        if ($user->isPortal()) {
-            if (!$entity->isAttributeChanged($idsAttr)) {
-                return true;
-            }
-
-            return false;
-        }
-
-        $assignmentPermission = $this->aclManager->getPermissionLevel($user, Permission::ASSIGNMENT);
-
-        if ($assignmentPermission === Table::LEVEL_ALL) {
-            if (!$this->hasOnlyInternalUsers($user, $entity, $field)) {
-                return false;
-            }
-
-            return true;
-        }
-
-        $toProcess = $entity->isNew() || $entity->isAttributeChanged($idsAttr);
-
-        if (!$toProcess) {
-            return true;
-        }
-
-        $userIds = $entity->getLinkMultipleIdList($field);
-
-        if ($userIds === []) {
-            if ($assignmentPermission === Table::LEVEL_NO && !$user->isApi()) {
-                return false;
-            }
-
-            return true;
-        }
-
-        if ($assignmentPermission === Table::LEVEL_NO) {
-            return $this->isPermittedUsersLevelNo($user, $entity, $field);
-        }
-
-        if ($assignmentPermission === Table::LEVEL_TEAM) {
-            return $this->isPermittedUsersLevelTeam($user, $entity, $field);
-        }
-
-        return false;
-    }
-
-    private function isPermittedUsersLevelNo(User $user, CoreEntity $entity, string $field): bool
-    {
-        $userIds = $this->getAddedLinkMultipleIds($entity, $field);
-
-        foreach ($userIds as $userId) {
-            if ($user->getId() !== $userId) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    private function isPermittedUsersLevelTeam(User $user, CoreEntity $entity, string $field): bool
-    {
-        $teamIds = $user->getLinkMultipleIdList(self::FIELD_TEAMS);
-        $userIds = $this->getAddedLinkMultipleIds($entity, $field);
-
-        foreach ($userIds as $userId) {
-            if (!$this->getUserRepository()->checkBelongsToAnyOfTeams($userId, $teamIds)) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    private function hasOnlyInternalUsers(User $user, CoreEntity $entity, string $field): bool
-    {
-        $ids = array_diff($this->getAddedLinkMultipleIds($entity, $field), [$user->getId()]);
-        $ids = array_values($ids);
-
-        $count = $this->entityManager
-            ->getRDBRepositoryByClass(User::class)
-            ->where([
-                'type!=' => [
-                    User::TYPE_REGULAR,
-                    User::TYPE_ADMIN,
-                ],
-                Attribute::ID => $ids,
-            ])
-            ->count();
-
-        return $count === 0;
-    }
-
-    /**
-     * @return string[]
-     */
-    private function getAddedLinkMultipleIds(CoreEntity $entity, string $field): array
-    {
-        /** @var string[] $previousIds */
-        $previousIds = $entity->getFetched(self::FIELD_COLLABORATORS . 'Ids') ?? [];
-
-        return array_values(array_diff($entity->getLinkMultipleIdList($field), $previousIds));
+        return $this->helper->checkUsers($user, $entity, self::FIELD_ASSIGNED_USERS);
     }
 }