OP -you've gone through the AG's office on this right? so mom is in arrears? do you get any tax intercepts for the arrears? do you know how much she is in arrears?
ok, if mom did get custody somehow, would the her arrears be applied toward CS from dad? how does that work?
op, are you sure your husband is looking at the right charts? for an 800 a month CS payment, he would be making about 63,000 a year... is that correct? he may be looking at 20% of the gross pay vs. 20% of net pay. if he makes 48000 a year, his payment would be 637 a month... not a huge difference but it's something.
at this point try to stop worrying about what if... you can what if yourself into a frenzy and it doesn't do anyone any good...