If you can be flexible with your friends, then you need to be just as flexible with your family. It's important to treat all the people you care about equally. It's not always easy, and many would say it's not even possible. But if you show people that you're at least trying to work with them, that's all that matters. So if a date has to be rescheduled, then it has to be rescheduled -- it's not the end of the world if plans have to be revised.