Some of what you cited has not been proven. There is no evidence that John Dowdy of Williamson is the son of Thomas Dowdy (b1759). Although it is certainly tempting to place him there. Maybe one day we can find something that confirms it. Plus the surname of the wife of that Thomas is not known. There is no evidence it is Armistead or any other name.
Lots of rubbish out thar on the net. Caution, my friends.