I don't know anything about Welch, and not much more about Kuwashima.
In 1935, the Nippon Athletic Club and NY Judo Club merged. Source:
http://www.blackbeltmag.com/archives...andoldman.html. The head instructor was Theodore Shozo Kuwashima.
Per the Social Security Death Index: KUWASHIMA THEODORE SHOZO Born Feb. 6, 1892 Mother’s maiden name. PURUKA KUWASHIMA Birthplace: JAPAN Died: LOS ANGELES.
In New York City, Kano held a press conference at the Hotel Astor on 16 July 1936. After the obligatory luncheon, Kano attended a judo exhibition at the Jiu-Jitsu Club located at 114 W. 48th Street. His host was T. Shozo Kuwashima, and the Japanese-American Courier (18 Jul 1936, 1) reported that "among the judoists were not a few Japanese and American women who have taken up the art." New York Times may have some additional details.
Remembered today mostly for his book written with Ashbel R. Welch (Judo: Forty-One Lessons in the Modern Science of Jiu-Jitsu, 1938), Kuwashima was born in Kagawa Prefecture on February 6, 1892. He studied at Tokyo Agricultural College, and while there, trained in judo. In 1916, he emigrated to the United States, and in 1919, he started a judo club in Chicago. During the 1930s, he taught judo in Stockton and other Northern California locations. Later he taught judo in New York and New Jersey. His grade was 5-dan. Around 1939, Kuwashima went back to Chicago, where he operated a judo club until a skin disease forced his retirement in 1945. In 1947, Kuwashima returned to California. Demonstrators shown in British versions of Kuwashima’s book included Ted Mossom and Stan Bissell.