It's been a long time since I had done anything on this McDonald line, but we were in VA in May, so I got back into it. After studying the court and land records, I am convinced that Alexander McDonald b. abt 1736 and d. 1811 in Jefferson, TN was the only child of Randel McDonald d. 1744 and Jane ?; and that Randolph, Margaret, Mary, Jane, and Sarah--children of Jennet Stark McDonald--were another family. I will be happy to share my findings with anyone who is interested--they're too lengthy to post here.
I hadn't realized until we were there how huge Augusta County was at the time, so it's not surprising that there were many McDonald families living there to confuse us.
I would love to know if any male descendants of Alexander have had their yDNA tested.