Which two Huxtable children interacted the least would you say?

I'm going to have to say Sondra and Vanessa.

I have to agree...Sondra and Vanessa. They seem to say very little to each other throughout the entire show. Weird!

The only time I even remember them having much of a conversation would be the episode when all of the kids stay at Sondra and Elvin's apartment. Even then, conversation was short.

Really though, I'd have to say that very few of the Huxtable kids had much interraction with their oldest sister. Maybe because Sondra was pretty much an adult from the start of the show. She always seemed to be a part of the adult story-lines rather than the children's stories.