My Walton family

My Walton family goes back to John Walton, Sr., who married Mary Sims. One of their children was Robert who I am told was married 3 times. The first was to Keziah Overton (the surname has not been proved) who was the mother of Robert. Robert had several children, one of which was Overton Walton. Overton had Simeon Walton, etc.etc.etc.
I am trying to prove the surname of Keziah. Would appreciate any help.