diff --git a/php/datasource/class-fieldmanager-datasource-post.php b/php/datasource/class-fieldmanager-datasource-post.php
index 3c5f5ffeb6..2253979df6 100644
--- a/php/datasource/class-fieldmanager-datasource-post.php
+++ b/php/datasource/class-fieldmanager-datasource-post.php
@@ -178,7 +178,16 @@ public function get_items( $fragment = null ) {
 			}
 			$ret[ $p->ID ] = $p->post_title . $date_pad;
 		}
-		return $ret;
+
+		/**
+		 * Filter items to be returned
+		 *
+		 * @param array $ret Available options, filtered by fragment.
+		 * @param array $posts Found posts.
+		 * @param object $this Datasource object.
+		 * @param string $fragment Search term.
+		 */
+		return apply_filters( 'fm_datasource_post_get_items', $ret, $posts, $this, $fragment );
 	}
 
 	/**
diff --git a/php/datasource/class-fieldmanager-datasource-term.php b/php/datasource/class-fieldmanager-datasource-term.php
index 52520f9e18..fa0c07737d 100644
--- a/php/datasource/class-fieldmanager-datasource-term.php
+++ b/php/datasource/class-fieldmanager-datasource-term.php
@@ -338,6 +338,15 @@ public function get_items( $fragment = null ) {
 			$key = $this->store_term_taxonomy_id ? $term->term_taxonomy_id : $term->term_id;
 			$stack[ $key ] = $term->name;
 		}
+
+		/**
+		 * Filter items to be returned
+		 *
+		 * @param array $stack Term list, filtered by fragment.
+		 * @param array $terms Found terms.
+		 * @param object $this Datasource object.
+		 * @param string $fragment Search term.
+		 */
 		return apply_filters( 'fm_datasource_term_get_items', $stack, $terms, $this, $fragment );
 	}
 
diff --git a/php/datasource/class-fieldmanager-datasource-user.php b/php/datasource/class-fieldmanager-datasource-user.php
index d917ad0cf0..5f4f6bc733 100644
--- a/php/datasource/class-fieldmanager-datasource-user.php
+++ b/php/datasource/class-fieldmanager-datasource-user.php
@@ -171,7 +171,15 @@ public function get_items( $fragment = null ) {
 			$ret[ $u->{$this->store_property} ] = $u->{$this->display_property};
 		}
 
-		return $ret;
+		/**
+		 * Filter items to be returned
+		 *
+		 * @param array $ret User list, filtered by fragment.
+		 * @param array $users Found users.
+		 * @param object $this Datasource object.
+		 * @param string $fragment Search term.
+		 */
+		return apply_filters( 'fm_datasource_user_get_items', $ret, $users, $this, $fragment );
 	}
 
 	/**
diff --git a/php/datasource/class-fieldmanager-datasource.php b/php/datasource/class-fieldmanager-datasource.php
index 82f4f3e07b..e53dd184ae 100644
--- a/php/datasource/class-fieldmanager-datasource.php
+++ b/php/datasource/class-fieldmanager-datasource.php
@@ -148,7 +148,16 @@ public function get_items( $fragment = null ) {
 				$ret[ $k ] = $v;
 			}
 		}
-		return $ret;
+
+		/**
+		 * Filter items to be returned
+		 *
+		 * @param array $ret Available options, filtered by fragment.
+		 * @param array $this->options All available options.
+		 * @param object $this Datasource object.
+		 * @param string $fragment Search term.
+		 */
+		return apply_filters( 'fm_datasource_get_items', $ret, $this->options, $this, $fragment );
 	}
 
 	/**
@@ -180,7 +189,7 @@ public function get_items_for_ajax( $fragment = null ) {
 			);
 		}
 
-		return $return;
+		return apply_filters( 'fm_datasource_get_items_for_ajax', $return, $items, $this, $fragment );
 	}
 
 	/**