The truth is always the truth, refile the moition and explain the situation, he cannot gain advantage, if you called it a settlement that is different, but the back support was not paid in full, right?
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No one knows exactly how the judge will react, but he/she certainly may inquire further into his finances.
You may be able to request that the Court compel him to swear to and notarize a Financial Disclosure Affidavit, which will serve as his sworn testimony that everything he says is true and accurate. Lying on a Financial Disclosure Affidavit garners very stiff penalties.
I highly recommend discussing this situation with a New York domestic relations attorney in a confidential forum as the Affidavit is a complicated document and mistakes may have far-reaching consequences.
We you say the "arrears are now double," this implies the order was in fact adjusted to reflect a new nuber on the arrears. Ideally, you could have endorsed the check "under protest" or "with reservation" & then cashed the check anyway. You will need to explain why you cashed the check with his notation & then its discretionary with the Magistrate as to whether to rule that the arrears would be zero. My inclination is to say the Magistrate will rule in your favor. That said, it behooves you to schedule a consultation with a Child Support lawyer in your area.
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