Let's Find You A Step-Sister!

Nina Elle and Angel Youngs are intimately involved in a taboo relationship. They decide to spice things up by inviting a new player into their bedroom dynamic - Angel's divorced classmate, Aria Banks. Nina takes charge of making this a reality, going as far as dating Aria's ex-husband to orchestrate the merger of their families.
Updates on Nina's progress are eagerly shared with Angel, with the suspense building as the ex-husband delays popping the question. Eventually, the news breaks that Nina has succeeded, the upcoming marriage sealing the deal for Aria to become the new stepsister. In due time, the marriage is celebrated, Aria officially becoming part of the family.
When giving her the grand house tour, Nina sneakily locks her new husband out, leaving the women alone to break the news to Aria that he vanished. With Aria feeling abandoned, Nina and Angel step in to offer comfort and assure her she is now part of their family unit - complete with the added bonus of taking intimate care of each other's bodies in a carnal sense.