Ok so everyone is showing up at your place, don't panic. Start making calls today, you have to do this the weekend before to give the family the chance to go shopping for food before the stores get too crowded. To host and get out of cooking just call and ask if they have a favorite grain or soy based meat substitute. Explain that you've been really concerned about the family's overall health and that you think this would be the perfect opportunity to set a new tradition of healthy eating. This year's feast will not include a turkey and will focus heavily on healthy grains and strange vegetables from the east. After a few calls you're likely to receive an offer to either move the dinner to another member's house or so many offers from others to bring dishes that all you'll need to do is make sure the plates and serving spoons are clean.
You can also go with my favorite standby and threaten the family with a platter full of turkey Hot Pockets or some grande packs from Taco Bell. That's worked really well! Also living in places not big enough to host the whole family with nothing but a dodgy looking alley and a treacherous set of stairs to get down that for the children is very effective in the automatic "not it" of family party hosting.