We have James Sandefur and Keziah in Barnwell, SC near our John Thornton.There is a William Thornton there earlier, 1772.There is a John Thornton and a Keziah Sandefur in Watagua, TN area in 1782 and on later.A good number of the people associated with our Thorntons are from York, Amelia, Goochland, Amherst.
There is a John Thornton in 1765 who is from Amherst, VA in the area.There is a John and a William Thornton in York/Hanover around 1750 to 1782 when the William dies.Many other "circumstances", too many to go into here.It appears they were in York, to Hanover to Amherst to SC.
I have NEVER found this Keziah Sandefur wife of James of TN/SC anywhere!Now there are Peter Sandefurs in the same area and time frame in SC.Have looked into him, but this family can not go back any further than his birth of abt. 1775 [?].I believe that this Peter "belongs" to your folks.