Well, Michael Ausiello of TV Guide may have given us a hint about the answer.
In his latest Q&A with fans, the television critic wrote about Kristen Bell's character:
Her presence without a doubt gave the show a much-needed boost. And remember my hint in last week's [column] about a surprising familial connection coming to light between two characters? Well, it may or may not have something to do with the call that Elle made to her daddy at the end of last night's episode.
Sounds like this would give the edge to Mr. Bennet, doesn't it? Could he have adopted Elle along with Claire? Let us know what you think about this possibility.