Nancy was with David Sells in the 1880 Census. Somebody misread the census and put the name as Wanay, but if you look at the actual record it is definitely Nancy E.
About the marriage to Alice Threadway, I've never seen the August dates. I've only seen 1883. The 1900 census record says they were married in 1884 so I figured Nancy died in childbirth and David quickly remarried to have someone to help take care of the kids.
I can't imagine Alice agreeing to let David name a child after a wife that he was separated from. (or that he would even want to!)
Would love more info - as Nancy Ellen Sells was my G-Grandmother .