Greg's and Kim's parents all spend Christmas at the Warner house this year. Not all is merry when a discussion about how every child has their 'A' set of grandparents (the ones they love) and their 'B' set (the ones they like) makes Greg realize his parents, Tom and Natalie, aren't Sam's 'A' set. When Greg sees Sam having a great time with Don and Jenny, he snatches Sam away from them, then tries to make his parents play with him. But Tom and Natalie are so dull and awkward around kids that Greg talks to Kim about it. She tells him it's not Sam's fault that Tom and Natalie are meek. Greg turns it into a competition, insistent on making his folks the 'A' grandparents. No matter what he orders them to do to win Sam over, Don and Jenny are one step ahead of him. Greg's angry when Don decides for everyone that they'll be breaking tradition by opening their gifts on Christmas eve. And he's furious when Don and Jenny give their gifts to him, Kim, Jimmy and Christine -- they've bought the cem