/**
  * Returns array of related children (excluding parent) for this make
  * @param DBModel $parent Must be a parent
  * @return type array
  */
 function get_children_models(DBModel $parent)
 {
     if ($parent->is_parent() && $parent->modelid > 0) {
         return DBModel::find_all_by_parentmodelid($parent->modelid);
     }
     return array();
 }