Bill and Chelsea Clinton are both going to be in the debate hall.
"You ought to be ashamed of yourself for jumping on my wife. You're not worthy of being on the same platform as my wife."
Depending on what Donald says and how he says it, Hillary could take the high road by drawing a parallel between her and Melania and other women and the way they have stood by their husbands in tough times. She could also invoke Chelsea and Ivanka's friendship and shame Donald for bringing Bill into the discussion when she has respected his family. This is chess--she will have a dozen moves for every possible one he makes.