In Robert White’s obituary/tribute in Golfdom, the writer mentions that Robert White was in charge of Wykagyl and 11 other courses in Westchester County.

We have to remember we have found articles in the past where Robert White was noted as the architect, but he didn’t actually design the golf course. North Shore and Shorehaven would be two recent examples (both in the New York Metro area). The article Sven posted clearly makes it sound like Robert White was already serving an advisory role at Ardsley and him doing the new work would have been a simple decision, but did he actually design anything or just construct from another architects plans?
A photo of Robert White from an advertisement:

I believe Montclair Golf Club and Greenwich Country Club were two other courses White consulted with in the 1920’s in addition to the clubs I mentioned above.
I’d like to see what Chris has as well. I’d also love to see the confirmation of Ross’ changes in 1919. Which holes were his 5 new holes? Why would he have to completely rearrange the golf course, if he wasn’t using new land to add his 5 new holes? Do we know the exact date of when they purchased the new land, and even if they didn’t own the land couldn’t they have had Ross take a look anyway to determine whether or not they should buy it? Just some questions I would have, considering I know next to nothing about Ardsley.