Oh boy is that right. mmmm Ramen noodles.....
Talked to the spouse; she believes FOC are morons too but that I will get something retroactive from them. Therefore, she is not willing to refund me my over payment.
I wonder if going down to the FOC building in person would help.
Searching the net for 'FOC Michigan retroactive refund' turned up several results, none of them indicating that the FOC ever hands out refunds, withholds part of support payments to make a possible future refund, etc. A lot of websites came up that explicitly stated that this is never going to be the case, and that such expectations is ignoring what the FOC is mostly about - a third party transferrer of funds. She's already got your overpayment, she's not willing to give it to you, she's certainly not going to be willing to give it to FOC.
It's possible this is just a misunderstanding on her part and your part on how the FOC system works, and my search could be quite incorrect. It would serve you both to speak to your lawyers, and get this clarified, and if possible, simply work out a deal on the side, or better yet, simply opt out of the FOC system and handle it like adults.