7th Heaven is looking to score a perfect 10 with viewers this February. TV Guide Online has learned that Bo Derek will guest star on a Valentine's Day episode airing Feb. 10 playing the mother of Kevin and Ben (George and Geoff Stults). Meanwhile, series regular Jeremy London will get a visit from his twin brother Jason in the Feb. 3 episode. It's the first time the siblings will appear side-by-side on TV.