Only one male is needed to test your hypothesis, but he must be a direct male descendant of Tobias - direct meaning male to male to male. I just today posted a letter to you on this. The fellow who you suggest was the father of Tobias was H. W. Williamston (note the "t"), age 26 in the 1870 census of Williamsburg County, SC. Hybert Williamson would have been only 17 years old in 1870 and still in Columbus County, NC. You get your male relative's Y chromosome DNA profile determined and I will help you compare it to mine.