My fiancé ex an him had a baby an we have the baby its living with us.. his ex the child's mother said she wants to sign off her right of him an give my fiancé full custody but she said its going to cost her money to do that.. an im just wondering if it really does or is she lying like always? Can someone plzz help me?

Not sure where you live, it appears that English is not your first language?

But in the US, it does not work like that, she can not just sign off on her rights, he would have to take her to court and even then they would only allow it, if you were married to him and wanted to adopt.

Besides that he can file for full custody and she would not ask for any visit rights in court ( but she could go back and ask for it to be changed unless there is an adoption)

His first stop at this point needs to be an attorney

If I follow what you said (and please don't type in all caps, but please use full words and sentences), your fiancée has a child with his ex (girlfriend or wife?) and she wants to sign over her rights to your fiancée.

No, as Chuck said it is unlikely (especially in the US) that would be allowed. Only a court can terminate parental rights.

What WOULD be allowed however, is for her to agree to give your fiancée FULL PHYSICAL and LEGAL custody for the child. Your fiancée would need to petition Family Court for such custody and, if the mother does not object, the court will ratify it. In such a case, any court fees would be paid by your fiancée and the ex would not have any expense other than showing up in court.