Why on earth would anyone want to have a dinner with people who don't want to actually have dinner? I mean, if she doesnt want the food, she can come over later. Im not sure if im more horrified that your mom is willing to pacify that whiny brat, or that your sister thinks she has the right to expect your mom to cook separately for her. I could totally understand having some consensus about the food during normal family dinners, but the whole point of thanksgiving is cooking particular types of food in accordance with myths about US history. Your sister should suck it up and go somewhere else. PS i hope shes vegetarian, except then shell throw a fit and your mom will cry.

Ok rant over, back to dealing with my own family.