You'll have to follow Addendum policy for site inclusion. If your hack fits the new identity exception, you can create a patch normally. If not, your patch will need to only contain your changes, and be applied on top of the existing hack.
An exact answer would depend on the details of the hacks in question. If yours falls into the complete category and the existing patch falls in the improvement category, you'll probably be able to submit it without making an Addendum patch.