All child support recipients are deceased

I am doing this on behalf of my stepfather. He had 2 sons that he was paying child support on, of the 2 both have passed away. He owes back child support but the amount is an accumulation from the time that his sons were living with him. He felt that since he was providing for them that he should not have to pay the mother. During this same time the mother was still claiming the children and was receiving assistance from the state, i.e. food stamps and housing. Here recently the mother has also passed away. Because of this back child support he has lost his drivers license and has had to resort to taking odd jobs here and there to help my mother pay the bills, he has now decided that it is time to get his life straightened out and try to move on but this issue is a major stumbing block. My siblings and I are willing to attest to the fact that the boys lived with him for several years, this willingess also extends to a son from a previous marriage of the mother's. Quite frankly, we are not sure where he would stand if we were to proceed, money is a tight commodity for all of us and he does not want to spend the money if he does not have a chance. So we need a little advice please.