How can I get my ex husband to remove my children from his dental insurance when they are not his biological children and wont do it?

This makes no sense to me -- I appear to be missing a critical fact; no provider should refuse to provide services because people have too MUCH insurance -- it is usually the other way around.  Your first step would appear to be working with the billing clerk at your kids' dentist's office; if that is unsuccessful, and (as you indicate, but do not explain the reasons for it) the court has refused your efforts, you might have to change providers.  But my guess is that there is an error of understanding, and that if you just start over, starting with the dentist's office, you can understand what is "really" the problem and therefor how to fix it, whatever it actually is.  If not, gather EVERYTHING, including all documentation, orders, motions, letters, and notes from each of the people and places reference, and bring the whole mess to a consultation with a qualified family law attorney.