diff --git a/Account/Account.php b/Account/Account.php
index c969c5663..cc2ba5125 100644
--- a/Account/Account.php
+++ b/Account/Account.php
@@ -271,7 +271,13 @@ class Account implements ArrayableInterface, \JsonSerializable
      */
     public function addPermissions(array $permissions) : void
     {
-        $this->permissions = array_merge($this->permissions, $permissions);
+        foreach ($permissions as $permission) {
+            if (\is_array($permission)) {
+                $this->permissions = \array_merge($this->permissions, $permission);
+            } else {
+                $this->permissions[] = $permission;
+            }
+        }
     }
 
     /**
diff --git a/Account/PermissionOwner.php b/Account/PermissionOwner.php
new file mode 100644
index 000000000..9c92a718c
--- /dev/null
+++ b/Account/PermissionOwner.php
@@ -0,0 +1,31 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.2
+ *
+ * @package    phpOMS\Account
+ * @copyright  Dennis Eichhorn
+ * @license    OMS License 1.0
+ * @version    1.0.0
+ * @link       http://website.orange-management.de
+ */
+declare(strict_types=1);
+
+namespace phpOMS\Account;
+
+use phpOMS\Stdlib\Base\Enum;
+
+/**
+ * Permision state enum.
+ *
+ * @package    phpOMS\Account
+ * @license    OMS License 1.0
+ * @link       http://website.orange-management.de
+ * @since      1.0.0
+ */
+abstract class PermissionOwner extends Enum
+{
+    public const GROUP   = 1;
+    public const ACCOUNT = 2;
+}
diff --git a/DataStorage/Database/DataMapperAbstract.php b/DataStorage/Database/DataMapperAbstract.php
index e8915a36d..db2638ceb 100644
--- a/DataStorage/Database/DataMapperAbstract.php
+++ b/DataStorage/Database/DataMapperAbstract.php
@@ -442,7 +442,7 @@ class DataMapperAbstract implements DataMapperInterface
                 $query->insert($column['name'])->value($value, $column['type']);
             }
 
-            if (!($isPublic)) {
+            if (!$isPublic) {
                 $property->setAccessible(false);
             }
         }
@@ -568,6 +568,30 @@ class DataMapperAbstract implements DataMapperInterface
         }
     }
 
+    /**
+     * Create relation
+     * 
+     * This is only possible for hasMany objects which are stored in a relation table
+     *
+     * @param string $member Member name of the relation
+     * @param mixed  $id1    Id of the primary object
+     * @param mixed  $id2    Id of the secondary object
+     *
+     * @return bool
+     *
+     * @since  1.0.0
+     */
+    public static function createRelation(string $member, $id1, $id2) : bool
+    {
+        if (!isset(static::$hasMany[$member]) || !isset(static::$hasMany[$member]['src'])) {
+            return false;
+        }
+
+        self::createRelationTable($member, \is_array($id2) ? $id2 : [$id2], $id1);
+
+        return true;
+    }
+
     /**
      * Create has many
      *
@@ -592,7 +616,7 @@ class DataMapperAbstract implements DataMapperInterface
 
             $values = $property->getValue($obj);
 
-            if (!($isPublic)) {
+            if (!$isPublic) {
                 $property->setAccessible(false);
             }
 
@@ -627,6 +651,11 @@ class DataMapperAbstract implements DataMapperInterface
                 }
 
                 // Setting relation value (id) for relation (since the relation is not stored in an extra relation table)
+                /** 
+                 * @todo: this if comparison is correct, trust me. however, 
+                 * manybe it makes more sense to simply check if 'src' isset(static::$hasMany[$propertyName]['src']) 
+                 * source shouldn't be set if the relation is stored in the object itself
+                 */
                 /** @var string $table */
                 /** @var array $columns */
                 if (static::$hasMany[$propertyName]['table'] === static::$hasMany[$propertyName]['mapper']::$table) {
@@ -638,7 +667,7 @@ class DataMapperAbstract implements DataMapperInterface
 
                     $relProperty->setValue($value, $objId);
 
-                    if (!($isPublic)) {
+                    if (!$isPublic) {
                         $relProperty->setAccessible(false);
                     }
                 }
@@ -829,12 +858,13 @@ class DataMapperAbstract implements DataMapperInterface
      * @param array  $objsIds      Object ids to insert
      * @param mixed  $objId        Model to reference
      *
-     * @return mixed
+     * @return void
      *
      * @since  1.0.0
      */
-    private static function createRelationTable(string $propertyName, array $objsIds, $objId)
+    private static function createRelationTable(string $propertyName, array $objsIds, $objId) : void
     {
+        /** @todo: see hasMany implementation, checking isset(src) might be enough. although second condition MUST remain. */
         /** @var string $table */
         if (!empty($objsIds)
             && static::$hasMany[$propertyName]['table'] !== static::$table
@@ -918,7 +948,7 @@ class DataMapperAbstract implements DataMapperInterface
 
             $values = $property->getValue($obj);
 
-            if (!($isPublic)) {
+            if (!$isPublic) {
                 $property->setAccessible(false);
             }
 
@@ -966,7 +996,7 @@ class DataMapperAbstract implements DataMapperInterface
 
                     $relProperty->setValue($value, $objId);
 
-                    if (!($isPublic)) {
+                    if (!$isPublic) {
                         $relProperty->setAccessible(false);
                     }
                 }
@@ -1263,7 +1293,7 @@ class DataMapperAbstract implements DataMapperInterface
                 $query->set([static::$table . '.' . $column['name'] => $value], $column['type']);
             }
 
-            if (!($isPublic)) {
+            if (!$isPublic) {
                 $property->setAccessible(false);
             }
         }
@@ -1441,7 +1471,7 @@ class DataMapperAbstract implements DataMapperInterface
 
             $values = $property->getValue($obj);
 
-            if (!($isPublic)) {
+            if (!$isPublic) {
                 $property->setAccessible(false);
             }
 
@@ -1584,7 +1614,7 @@ class DataMapperAbstract implements DataMapperInterface
                     }
                 }
 
-                if (!($isPublic)) {
+                if (!$isPublic) {
                     $property->setAccessible(false);
                 }
             }