I'm trying to get my dads benefits through social security they won't give then to me unless my mom can get a copy of his tax return showing he claimed me as his dependent and the i.r.s won't give it up because they didn't file their taxes jointly as a married couple my question is what other way can I show that I'm his daughter I need something legal or certified help!!

I take it your parents weren't married, correct? Otherwise your parents' marriage certificate and divorce papers would establish that you were born while they were married. But since he's not listed on the birth certificate, I'm guessing this won't work for you. Were there any court documents that required him to pay child support that you can get a copy of? Do you have any documents that can be used to prove that you lived with your father at least part time - things like school reports that he may have received?