Winchester, Tennessee, is where Thomas went after leaving North Carolina. His son William, born in Buncombe County, N. C., in 1805. He did not go to Tennessee but remained in the Buncombe-Burke-Yancey County, N. C., area. He married (1) Matilda Jane Penland. She bore him children until 1841 and died shortly after childbirth that year. Wm. married (2) Eliza Madalyn Angel and bore him another 14 or 15 kids, according to which account one goes by.
I don't have Thomas Westall moving to Tennessee until 1811. It's possible that he heard of opportunity there from a relative (Westall/Vestall). One stroke of a pen by some record-keeper easily could have created Vestall from Westall somewhere along the way. Especially some Westall who heard the name pronounced by a German. The Westall name goes way back in England.
More of my Camfield ancestors in the colonies than not wound up going with the flow and becoming Canfields due to record-keepers, gravestone carvers, etc. And there was a contemporary Canfield who arrived in Connecticut Colony in the mid-1630s about the same time as my immigrant ancestor Matthew Camfield.
It sure is a big coincidence that your William was born in North Carolina, then wound up in Franklin County, Tenn.
My Thomas Westall was a slave-owner both in Tennessee and in Texas in the early 1830s.
My guess is that if you're not ethnically German, you share Westall ancestry of some sort with my wife.