Can I still collect arrears after adoption

My new husband is going to adopt my son, and my son hasn't had any relationship with his biological father in years(my son is 11). When there was visits they were supervised and sporadic.

The biological father owes me $24k in back child support and I am in the middle of a QDRO to get money from his retirement. I just had to go to court and he is threatening to try and see my son again if I do not drop the QDRO.I am in a panic and we are trying to get the adoption paperwork drawn up immediately.

My concern is that all the money he owes my son for the past 11 years will be lost if my current husband adopts him. Can you help me?