Condition user roles

Hi support,

I would like to wrap up some conditions around the Payment Packages visible on the Submit New Listing page (for example by User Role or some other checks).

I did it already changing the source code but of course, all changes disappear once I run the next GD update.

Is there a way I can copy the necessary function, de-register it in functions.php and register the new one with my changes, so it can keep up the changes through the GD updates?

Thanks.