How do I get my daughters "sperm donor":) biological father to sign off rights to her? And is there any suggestions on how to get him to because he doesn't want to because he thinks he can claim her on taxes. I know he can't but he thingks he can. But he doesn't want anythign to do with her he would rather spend time with his 16 year old girlfriend when he is almost 23 then with her but I don't really mind because my fiancé has been her daddy for 3 years now and he actually wants to adopt her when he can get the other guy to sign off his rights

First unless he is paying for the majority of her support ( child support does not court) he can not claim her, and in the child custody agreement it should say if he can, and if he can on what years.

So I will assume you are claiming the child on your taxes ? The IRS will not allow both of you to claim the same child.

But just be sure you are forcing him to pay his child support, that would be more than any refund form IRS, and when he knows he can stop makinig child support payments, when the child is adopted, most liekly he will change his mind