I've got it now. Sure wish one of my distant Alexander cousins would come forth to participate in this study. I would even be willing to pay for it!!
My FKA is James Alexander b. 7 Apr 1749 Chester County, Pennsylvania / m. Elizabeth Ross / d. Dec 1835 Iredell County, North Carolina.
They had sons (also daughters but they wouldn't be useful for the yDNA test so I won't list them here):
1) Reuben m. Jean Wilson and settled in Indiana. They had a large family. 2) John Wilkes m. Mary unknown and settled in Rutherford County, Tennessee 3) Horatio Gates m. Mary unknown and settled in San Augustine County, Texas and had a large family. 4) Alexis - d. in Rutherford County, Tennessee. I think he did not marry or have children 5) Oswyn/Oswin - settled in Rutherford County, Tennessee and had a large family. 6) Elam - lived in Tennessee but d. in Bibb County, Georgia. He married but I don't know if he had children.