March, 1938 Charles R. Stinson dies at the age of 48. Most of the next-of-kin are still together in the 1940 N.Y. census. As in his death notice, no mention of Mrs. Charles R. Stinson.

How the company assets (considerable) came to Irving Prosky isn't explained in the sources. Fact is they did and so, finally, we arrive at the famous Soviet Records era and a very distinct shift in the Stinson Trading Company business model. To recap:

“(Herbert) Harris and Prosky operated the concession to sell records from the U.S.S.R. at the 1939 World's Fair in New York City, but when supplies fell short of demand he and Prosky set up their own record label to produce copies of Soviet and other eastern European recordings, including recordings by the Red Army Chorus.” [wiki]

Herbert Harris may have already joined up by 1939. The rest of it never happened.