I had not found the Charles Seeger article before, even though it is posted on FOTMD. Perhaps it is new here.
To me, there are some interesting side issues. It barely references the Ritchie family, although it does have a photo of Jean, and mentions her husband George Pickow's instruments, not disclosing that his shop was Brooklyn, NY and his connection to Appalachia was Jean.
According to Jean Ritchie's books, Charles Seeger had collected songs at the Balis Ritchie home when she was a child. At that time there was a dulcimer in the home, and Balis was more willing to play it than to sing. Didn't Seeger ask Balis about the instrument, or did he distrust what he was told?
I believe that at the time the paper was written, Jean was in New York, playing on the radio with Woodie Guthrie and Leadbelly. She surely was crossing paths with Pete's dad.
Seeger collected a tune at Arthurdale, WV while Eleanor Roosevelt was holding a square dance there. The fiddler was from the area I pass through daily, and was well known here back in the 1960s and 70s. As best I remember, Seeger put in the the Smithsonian Collection and it was recorded by the New Lost City Ramblers as "collected by Charles Seeger," not crediting the fiddler.
I can't put 100% faith in what he wrote about Appalachian Dulcimer history.