Tom MacWood,
If Tillinghast saw the plans for Merion at Garden City, or even if the saw them hanging on Macdonald's wall, all the better!
He still saw the plans prior to construction, he spoke directly to CB Macdonald about them, he had many good friends among the Merion membership, the best being Howard Perrin, and he also knew what all the terminologies meant from laid out to architecture. Hell, one of his quotes I've only seen one other place and that is in the April 19, 1911 Merion Minutes!!
And with all of that, when Merion opened he did not credit CB Macdonald with the course in his length review for American Cricketer, and instead said Hugh Wilson deserved the congratulations of all golfers!
Then, in case there was any remaining doubt, and because it was so sad that so few knew the truth, he wrote the conclusive proof in 1934, as seen above.
Never did he mention anything about Barker, and Alan Wilson also made very clear that Merion did NOT use a golf course architect.
This Barker thing of your's is thinner than an Ethiopian model. We can go over it again, but almost none of those courses were opened in June 1910, or if they were remodels only few had their work done by Barker by that time.
By the way, are you seriously trying to convince us that A. W. Tillinghast didn't really know who designed Merion?!?!?