Definitely talk to your state's child support division if they're involved. They'll know what sort of things he might be trying to pull and why - and how to deal with it. They (or a lawyer) should also be able to tell you whether, in your particular situation, the $15K really is all you're likely to get or if you can realistically get the full amount.
I'd start with the CS division and a chat with a good lawyer. (Let the lawyer know that, for the moment, you're looking only for advice and just want to pay for a consultation.) I have *zero* sympathy for anyone who avoids CS payments for 12 years, but each case can be so different that you need someone familiar with your local laws giving you sound advice. Don't sign anything before you get that advice.
Good luck!
I'd start with the CS division and a chat with a good lawyer. (Let the lawyer know that, for the moment, you're looking only for advice and just want to pay for a consultation.) I have *zero* sympathy for anyone who avoids CS payments for 12 years, but each case can be so different that you need someone familiar with your local laws giving you sound advice. Don't sign anything before you get that advice.
Good luck!