diff -u b/role_delegation.module b/role_delegation.module
--- b/role_delegation.module
+++ b/role_delegation.module
@@ -179,6 +179,7 @@
         'type' => 'options_buttons',
         'weight' => 1,
       ])
+      ->setSetting('handler', 'role_change:user_role')
       ->setDefaultValue(DelegatableRoles::$emptyFieldValue);
   }
 
only in patch2:
unchanged:
--- /dev/null
+++ b/src/Plugin/EntityReferenceSelection/RoleChangeSelection.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace Drupal\role_delegation\Plugin\EntityReferenceSelection;
+
+use Drupal\Core\Entity\Plugin\EntityReferenceSelection\DefaultSelection;
+use Drupal\role_delegation\DelegatableRoles;
+
+/**
+ * Default plugin implementation of the Entity Reference Selection plugin.
+ *
+ * Also serves as a base class for specific types of Entity Reference
+ * Selection plugins.
+ *
+ * @see \Drupal\Core\Entity\EntityReferenceSelection\SelectionPluginManager
+ * @see \Drupal\Core\Entity\Annotation\EntityReferenceSelection
+ * @see \Drupal\Core\Entity\EntityReferenceSelection\SelectionInterface
+ * @see \Drupal\Core\Entity\Plugin\Derivative\DefaultSelectionDeriver
+ * @see plugin_api
+ *
+ * @EntityReferenceSelection(
+ *   id = "role_change:user_role",
+ *   label = @Translation("Role change"),
+ *   group = "role_change",
+ *   weight = 0,
+ * )
+ */
+class RoleChangeSelection extends DefaultSelection {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateReferenceableEntities(array $ids) {
+    $result = array();
+    if ($ids) {
+      $target_type = $this->configuration['target_type'];
+      $entity_type = $this->entityManager->getDefinition($target_type);
+      $query = $this->buildEntityQuery();
+      $result = $query
+        ->condition($entity_type->getKey('id'), $ids, 'IN')
+        ->execute();
+      $result = array_merge($result, DelegatableRoles::$emptyFieldValue);
+    }
+
+    return $result;
+  }
+
+}
+