SO bet is a birdie loyalist no matter what, so i'm afraid with the way things have shaken out with bird/mal they likely wouldn't be talking much right now either, but before that! bet always looked up to her sisters a lot and wanted to be "like" them, so as such i'm sure she was the annoying younger sister when they were kids and then once she was older and less obnoxious they could have been real close friends outside of birdie?