David Stamm, that is a fairly well known photo taken at the first meeting of the ASGCA. It appears on p153 of C&Ws book, and all the archies are named.
As for Willie Watson's middle name... I'm going to guess "Kidd". Back in the first decade of American Golf, R/. Foulis brought Watson over to help him with laying out Minikahada. Willie was the super there for several years and started splitting his time with winters in CA and summers back east, including Charlevoix, Belvedere. The head pro at Mini for many years was Willie Kidd, also brought over at that time from Monefieth Scotland, near St Andrews, where they all seem to have spawned, under the tutelege of Old Tom. I'm thinking it was a family affair and they all had some kissing cousin relationships. "Kidd" could be a family sort of name... used in middle names as well.