I'm pretty sure what he pays in child support is based on both yours and his income, so is the back support. I've been through a lot with custody, attorneys and court over my 16 year old daughter. I've used William Harrington he is in Danville and is a good attorney. But the best advice I can give you in this situations is for the two of you to agree and work together rather than argue with an attorney. It is very costly, the Hendricks county prosecutors office should be able to help you with arrearage based on both your incomes. You may be able to do a google search for a child support calculator and this will let you know what you are entitled to before you spend money on an attorney. The prosecutors office if it is like Marion County is basically free and in you favor if he is not paying. Also, remember to be the best parents you can be to your children and not to discuss this with them, it will only make them dislike you or him at a latter date in time. They should only be worring about kid stuff not adult matters. I also have 3 raised daughters from divorce, it is best to only say good about the other parent and don't point out their faults, kids don't see those at a young age but will when they get older.