Check with teh laws. Somewhere (I think it's FEDERAL law, but I might be confused again) it says that both parents have the absolute right to have everything. If you are trying to do this on your husband's behalf, the insurers might not let you... but otherwise, have him send them a copy of the law that requires them to give him this information. Or simply don't pay until she gives him a release of infomration form for him to get all this information from them so that he can be assured that what she's chargign him for is fair and that she's actually paid it. And if she has not paid it herself, he should be paying the insurer or doctor directly.
We watched ChatterBox go through something like this not too long ago and it just sounds like a real mess... do what you can to see tha tit doesn't get that far as to create such a mess that will be as impossible to get out of. Good luck.