Hi, so my daughter's father wants to take my daughter to Colorado to visit his family. I was fine with it until I discovered that he wouldn't be staying there with her, and she is only three. When I expressed this to him he informed me that him and his mother had already booked the flight and it would cost $498 to change it. A cost he tells me I have to pay since they had already booked the flight. So my question is am I obligated to pay this?