Back pay child support?

-My dad explained to me and my mom that he still owes child support, even though the child from his first marriage is already twenty two and just had he first child. But the thing is its the interest that is built up over the years and not the actually child support money. He is willing to pay the amount, but what we would like to know is there a way or is there is someone that can help him reduce the interest amount so he can be able to pay if off sooner than never because the amount the never goes down. Please help us with some advice and not ugly remarks were just looking for help!My mom was on the other end of the spectrum and the same thing happened with my dad and I am 26. The courts find out that he still owed money to us and they took over. My mom tried everything she could to say to the courts that she doesn't need the money and they said it CANNOT be changed and that she could give the money back to him each month if she wanted, and that is what she does each month when she gets a check. The amount that comes to her is interest as well. Hope this helps.
He 'll to get a lawyer for that!

The courts usually don't let free money get out of their sights!!