Personally I think they are involving you too much in their affairs. Bottom line is he pays you for the days you have agreed on and if the child is not there then whatever-it doesn't matter where she is. Sorry to say but the courts don't care about routine and likely mom will get her way anyways. I would take a step back and distance yourself from the drama. Tell dad your fee is your fee no matter when the child attends and that is it. No letter and don't get involved.