We share 50/50 custody of my step-daughter and have no support order. In the order it states parents agree to pay for one-half of costs of the the childs school-related activities. She decided to take up flute, (5th grade) and the mother went out and bought a $800 flute with no discussion to the father. Then she sends the receipt to the father and expects payments. He has 2 other kids and needs to live a little more frugile then one with one child would. He had access to 2 second-hand flutes and offered them instead, since she is a beginner it should have sufficed. She refused, and said the child has been using the new one and prefers it. Does he have an obligation to pay on demand whatever she chooses to purchase without discussion? She filed contempt for not paying for 1/2 of the activities.