Hi again. Have looked through my huge folder of Isbell data. The last source I had linking (quite firmly) James and Joseph Isbell has changed his e-mail address from the one I had in 2005, so my new note to him bounced back. He was a Paul V. Isbell, but who knows where he was.
There was also a Sidney S. Isbell who shared all of the info with James, including year and place of birth, year and place of death, year of marriage, etc. I have a copy of his will, which mentions his dying of a disease and leaving two minor children. Might be the same guy. The combination of Sidney and Isbell isn't as uncommon as I'd thought.
So, if you find a Paul V. Isbell he might have some proof of relationships. Let me know.