OPfamilyof5,
Thanks for joining us. I'll do my best to answer your questions below.
1.) To my knowledge, chid support can only be changed upon motion of one party (or their attorney of course). Have you ever had child support enforcement involved in your case? If so, the court would have the Kansas dept of Children and Families file the motion. I'm not saying this has never happened, but I don't believe child support can be "automatically changed as you stated. A motion must be filed.
2.) The opposing attorney will ask for w2s and income info if a motion is filed, but they can also request them at any time. BUT you can and should do the same thing. All is fair, so you should be provided with your ex's income info.
3.) your wife's income will not be included. With regards to a joint return, you can simply object to the request in writing (send it certified mail return receipt) stating that you will gladly provide your info, but you should black line all of your wife's info and then make a copy of it.
4.) see #3
5,6,7,8) I think your child support is completely wrong and you are getting hosed. You should not be getting a 15% adjustment, you should be using the shared custody formula. Your attorney has not been doing his/her job. You should be using the Multiple Family Adjustment for your 2yr old daughter. Search around this site for info on that. You also should not have to pay child support for your 18yr old unless you really want to or unless you've agreed to already. They court cannot make you pay after the child is 18 unless it was ordered in the divorce decree. A new order which was last reviewed in 2007 would be a complete review of all parameters. Daycare would be removed if it no longer applies, insurance would be calculated again, and you should be put on the shared custody plan.
Sounds liked you've tried to be a nice guy and an open wallet. That all sounds great, but the courts seem to either hang you out to dry for underpayment or for overpayment. Once you start overpaying, the court may try to say you've "traditionally paid." Child support will not just change without a court order. If you're fine with whatever happens, you could just agree to the motion your ex is about to file and avoid the confrontation. But if you'd like to make things fair, you will need an attorney who knows what fair is. If your daughter is 18 and will graduate in May, you should be preparing a motion to be heard about 1 week after graduation to remove her from CS and readjust for your other daughter.