Yes, it's possible. But the court may offset any child support to which he would otherwise be entitled by the amount he owes to you. Custody and child support are viewed as separate issues, so the fact that he's behind doesn't necessarily mean he can't try for custody. The court is going to look at a number of factors (http://www.ai.org/legislative/ic/code/title31/ar17/ch2.html) to try to determine what is in the child's best interest. By the way, the longer the boy lives with Dad, the better chance Dad has at getting custody, because the court will favor stability in a situation like this.
Thanks for the question.
Indianapolis divorce attorney
The foregoing is not intended to be specific legal advice, but rather general information. Because of the nature of this online, non-confidential forum, and because each and every family law case is different, it is impossible for any attorney to consider all of the facts of your specific case and provide a concrete answer. If you require specific legal advice, you should retain a qualified attorney in your area.