Just chill a bit... Yes Becca is highly manipulative, but I see her as having a serious Daddy complex. So in order to fill that need she needs to corupt frank and set him up with Lilly. Knowing Abby soon will break Frank down herself Bedda has set the stage She knows that a relationship with Frank without the sisters would rip open the family. By involving all the girls with Frank means that all share in the secret and still holds the cohesion of the family without the risk of breaking up the family.She says she is doing it out of love. That is not love. That is someone who gets off on making the puppets dance.
I've had to deal with a manipulative Ex-wife and I don't see this as quite the same thing. At least that is my opinion . I hate a mind fuck as well as you, I just don't see the malice that's all.