My husband's exwife took their son to a dentist that was not covered by insurance. My husband has full dental insurance on his son. She received a $900 bill and says we need to pay 60% of it (based on the divorce papers). We never agreed to her taking him to a different dentist that was not covered. We would have only had to pay under $150 for the same procedure. Are we responsible to pay for decisions she made without consulting us and for deciding to take him to someone that is not covered??