Who is this person?

[Rob Wick]

Sorry Mike, but I'm not that clever.

Roger nailed it. It is Worthington Chauncey Ford. Tarbell and Sandburg knew him because Ford worked with Paul Angle and Oliver Barrett to prove the Wilma Minor letters forgeries. While he knew Beveridge for several years, it was Ford that Catherine Eddy Beveridge chose to finish her husband's second volume on Lincoln.

I didn't use this clue, but Ford was a direct descendant of Noah Webster on his mother's side. In 1902 his brother, Malcolm, shot and killed another brother, Paul Leicester Ford, who was a novelist and biographer. Here is the New York Times account of the murder.

https://timesmachine.nytimes.com/timesma...geNumber=1

Best
Rob