My question involves a child custody case from the State of: Missouri

My ex, after nearly 2 years, has decided to file a motion to modify visitation and residential custody based solely on his interpretation of the children's preference. they are 11 and 15, and the 15 yr old has a cognitive disability diagnosis of Asperger's Syndrome. We currently split visitation nearly 50/50. He is requesting a change to one day a week and alternate weekends for my visitation. He wants me to just 'agree' to this change - of course, I do not wish to. It is my opinion that it is not in their best interest, medically, behaviorally, or physically to spend less than 50% time in my care.

I am looking for advice/opinions on how the courts would view this request, and what my 'defense' should look like. I currently do not have legal representation and have not received any paperwork. My understanding is that he has worked with his lawyer and is ready to file the motion.

He is also asking for my financial information, stating that it's necessary when filing a motion to modify. I do not wish to provide this information to him. Do I need to?

Thanks for your attention and assistance.