Providing a different hook in SubmissionSearch.inc.php

Hello,
I’m developing a theme for a client.

I need to improve the search form using for retrieve submission filtered by categories, I would like to use the hook in SubmissionSearch.inc.php in order to modify the query, but the existing one doesn’t allow to modify the query.

What is the process to request a new hook or to provide a possibile implementation for a new one?

Kind Regards