This isn’t your typical Cinderella story. The late billionaire Bruce Wasserstein’s mistress is reportedly preparing to fight for the legal rights of a child she gave birth to five years after his death, using embryos he fertilized and froze while still alive. The mistress, Erin McCarthy, had one child with the former New York Magazine owner before he died in 2009 and another nine years after his death, using one of the frozen embryos. Four more embryos still remain, and lawyers for McCarthy say they are exploring whether they would have a claim to Wasserstein’s fortune, too, should McCarthy choose to carry them. The question arose as part of a $100 million lawsuit McCarthy and her eldest daughter, Sky, filed against Wasserstein’s five other children, describing Sky as “Cinderella” and her half-siblings as “evil stepsisters” who refuse to turn over her fair share of his fortune. A spokesperson for the executors of the estate and the trustees of Wasserstein’s family trust previously told Page Six: “The executors and trustees have at all times acted in accordance with their fiduciary duties. We regret that this matter continues to be litigated and will vigorously defend against these meritless objections.”