What would make her do this? (BM)

id fight it,tell her u guys go in half for everything aand u have bills just like everyone else.

There could be a lot of reasons for this, ranging from she has found out (or thinks she has) that you all, while paying what you legally have to, haven't been paying a fair amount (like if she got the order of support with him making one income amount, and, over the yrs, he's been getting a LOT more, and she never had the order increased to reflect his higher income bracket, which honestly should be done). OR - the dd is almost 18, and the mother is realizing that the child support will stop soon, and she's depending on that money for more than just supporting the child directly - like, say, part of it goes towards paying the rent (a fair expense, since the dd lives in her house, but on the other hand, once she's not in high school and over 18, it's not your responsibility to help pay the mom's rent), so she's trying to "stock up" on some money now while she can.

Could be lots of things - talk to her and a lawyer and see gl!

Or the cost to support her is higher, driving expenses, school expenses, costs of college testing etc.

If you are paying half of everything....like those expenses above, she's very lucky!!! My ex didn't even pay half of court ordered medical expenses........

This is very common. My brother's ex would take him to court regularly (every 2 years or so) and ask for more child support. she and her attorney figures since he would get an increase in pay, his kids should get more support.

Is she (sd) going to attend college? Maybe her bm wants it for that purpose? Or, maybe she is just a b@@@H!

Good luck to you all.