Thanks for the reply. There is a possibility that your wife's William could be a younger brother to my older Michael Coffman, born abt 1767. My ancestor Michael's father was also Michael. Needless to say I haven't got enough information to verify this, but there was an older Michael Coffman that lived most of his life in Knox county along with my Michael.
They last show up on the 1860 census & on the 1870 census some of Michael & Sallie's children are very young living with other families in Knoxville. This leads to believe that Sallie had died by that time.
In 1880 my gg-grandfather Thomas J. was living in Loudon county working in a mattress factory.
If you ever find anything on other Coffman's in your area please let me know. I'm always searching for new connections