I do like to help out and be accommodating when I can, but I'm not inclined to change my schedule which affects my classes, work and DS's schedule, because of your poor planning. Looking at a friend and my college department, both want me to change things but means I have to run around to try and rework things. I understand it's easier for you to ask me to make changes than for you to work something else out. It's not easier for me. My answer is No. You do have other options, use them.