My daughter is 17 & i started to pay child support for her on October of 07 till she is out of high school. No problem here. When they asked her if she wanted backpay she said no. We all signed & been paying up like i am supposed to. She recently asked me to help her pay to get our daughter a car but i cannot afford it & my x is very upset about this. I have a feeling she is going to try to change her mind now about the backpay. Is it possible for her to do this, it has me worried. She is in Colorado. I told her i would help otu with like $300 but i cant afford $1000 for a downpayment, she wants to go half.