Ongoing annoyance

I hate it when family members plan parties or get-togethers and then invite us a day or two before the date and regardless of whether or not I'm busy I have to go because they're family. It's like they're riding on the fact that people will go because it's family, despite the fact that they are being rude and inconsiderate hosts by not giving us ample time to free up that day. Manners is definitely becoming nonexistent!