In last night's [terrific, I think] episode, in the school gymnasium before Bart moons the flag, you see Marge's mom sitting with Patty and Selma. When was the last time we saw her? She doesn't even appear in the background for all these years, and yet she's still alive. Marge must not like seeing her mother.
Last time we saw Jackie Bouvier was the episode where she had an affair with Grandpa and Mr. Burns.