For gay parents who have a child, obviously they can't both be called "mom" or "dad," so hearing parents will have "mom" and "mama" or similar...what about Deaf gay parents? I can't think of more than one sign for mom or for dad.
The only thing I've though of so far is doing something like "mom" (in ASL) for one and "mom" with wiggly fingers for the other. Your thoughts?