Did Susan knew all this time who is the real father?
I guess she at least took into account that such a possibility exist since she slept with both of them within a week but did she knew for sure who's the father?
I can not remember what was her reaction when Frank told her about his futility.Not that she could have guessed about his fertility problems but was she shocked like he was or less because she knew all this time that he's not the real father?