Maybe II would not, but remember the request-first search is a Marriott week to start with. Do they know that one of their weeks is being used for an II search?
Only if II told them, which I doubt. II had no reason to tell them and Marriott never cared. That may have changed with DClub. It might be worth it to check II's privacy policy to see if that's addressed.
I don't know, but it is not as if they know about a Starwood resort involved in a search. (Come to think of it, Starwood is rumored to control what an owner can deposit, aren't they?)
I don't know much about Starwood, but I believe that's correct.
Who knows, II's software may be sophisticated enough to identify and execute a three player trade [A-->B; B-->C; C-->A] or even more.
If they are all Marriotts perhaps so. But that would require the same level of knowledge as my original theory, would it not?
Just speculation on my part, but II might well have the capability of identifying and executing a three player trade. Its doubtful that Marriott does. They don't need that capability with a points based system.