I'm not sure we're related either, but I have seen it mentioned (speculated?) that there was a brother named Thomas to John F and William (Sr) Willey. John F and William were involved in the Natchez Trace survey. I do believe Thomas was related (just not positive he was their brother), although I tend to lean that way....so it confuses me when you say the Thomas Willey from Dickson Tennessee's father was Thomas. I was fairly certain it was Joseph. I hope someday to be able to spend time on that...but for now, I'm still trying to track fairly newly discovered family relations (Jane and Harry/Harvey Willey who could have been mom/son -- but respective DsOB off a bit) to my William Abe.
I wish you the best!