the daughters and Bianca have no idea what Ellen looks like?
There is something about the movie that bothers me, though it was good otherwise. Ellen returns to her home, and she sees her two daughters in the swimming pool. They, at the time of her disappearance, were babies, and they were too young to remember her. Ellen greets her daughters, but they don't recognize her. I can't believe that. I mean, the only way this would be possible is if Nick had removed all photos of Ellen in their home, and never showed them to their two daughters. It seems selfish for a father to never show his daughters any photos of their presumably deceased mother. Even if they don't remember her, they could still feel the pain of the fact that (as far as they knew) their mother was dead, and that they would never know her. Then again, the beginning shows Nick to be somewhat insensitive, in that he had Ellen declared legally dead, and married Bianca immediately afterwards.
Also, when Ellen poses as Helga, the Swedish nurse, Bianca does not recognize her either. So, we are expected to believe that Nick removed all photos of Ellen, and never showed his new wife photos of his first wife whom he lost.