This article is written for those who want to get to the bottom line answer, without wading through all of the argumentation. Keep in mind that this is a complex problem, and many people have invested a considerable amount of themselves in a particular position. If this is the only portion of this series of articles that you read, you are likely to unhappy with the views expressed here. You may still be unhappy if you read everything, but at least you'll have given the subject matter due consideration.
Here's the answer:
Fleming, 1971 is in substantial error with regard to the ancestral line of JB Cowan. JB misunderstood the stories related to KBI and CBI events in his family. He combined a series of stories related to different members of his family with other stories. The key event is his story concerning the KBI of Major John Cowan and the CBI of his wife Mary Walker on the Clinch River in southwest Virginia. These people probably did not exist. The story is grounded in a factual event for which we have a first person account, namely the KBI of John Pauley and his wife Margaret Handley Pauley in 1779 near Bluefield WV. Margaret was the sister of Samuel Handley who was the brotherinlaw of the Major John Cowan who married Agness Martin. This Major John lived to old age, dying in 1837. This Major John was the brother of JB Cowan's grandfather, James Cowan. JB attached a story associated with the family of his aunt Margaret Handley, to the family of his Uncle Major John Cowan. Since Major John Cowan is known to have lived to a ripe old age, genealogists have assumed there was a "second Major John Cowan who died during the Revolution."
It is important to note that Fleming identifies the Major John Cowan who was KBI'd on the Clinch as the son of Samuel Cowan = Ann Walker. This connection is incorrect. While Samuel Cowan and Ann Walker had a son John Cowan, he was probably a minor at the time of JB's story (c1779), and in any case, lived well after that date.
The reader is encouraged to read the supporting analysis for the above conclusions.