How to extend relation Config October CMS

how to extend controller to add a config relation fileds.

for now i found that i can add a new file like this

 myController::extend(function($controller){$controller->relationConfig = '~/plugins/path/languages/config_relation.yaml';        }); 

in this situation the method erase my config files already exist and add a new one so it trigger an error because the others already relation behavior not exist.