We go around around on the title "Disproven Existence". It's the best we could come up with, but as anyone knows, it is technically impossible to prove the non-existence of anything. So if anyone can come up with a better one or two word title meaning "we can find no evidence that a person by this name existed," I'm sure we'll entertain it.
It appears to me there are two facts here that we are pretty sure of: (1) William Witt had a wife, whose name is Unknown. (2) There is a profile for a woman named Daux for whose existence we can find no evidence, but there are profiles for her all over the internet.
So I still favor ending up with (1) a Disproven Existence profile for the woman named Daux, for whom there is no evidence that she ever existed, or married William Witt, and a (2) second profile for an Unknown woman who married Witt and bore his children. The profile for the woman named Daux will educate people who believe she exists, or who would try to re-create her profile if there weren't one already, and the profile for the Unknown woman will hopefully keep people from adding a fake wife to William Witt. In addition, I would suggest Project Protecting PPP William Witt's profile, if it is not protected already, once he is linked to a wife Unknown.