Tony--
The Travis Society's Garden City Country Club file is very thick, with many local reports about the new course that Travis designed in 1916. In addition, we have a Brooklyn Eagle article, April 21, 1928, that details several changes to the GCCC course, e.g. replacing chocolate drops with bunkers alongside one fairway, etc. At no point does the article mention a designer/architect. The club website history mentions a "rejuvenation" by Brian Silva, in the 1980s, and we know that Keith Foster, and his associate, Kevin Hargreaves, was involved in bunker work, etc., beginning in 2007.
I have found no mention of Colt/Allison being involved, but perhaps there is more information available, somewhere, that would connect them with the 1928 course changes.