I need some clarification here. Traditionally add-ons are for all members, blue and white. So that would usually mean that anyone with a membership can add-on, and applied here would mean anyone with a membership could add-on and then book starting May 16, but then it says "before bookings open to all other Members" on July 27 (first day of EPCOT Food and Wine for you calendar keepers).
If all members can begin adding-on May 7 to book May 16, what's left to make "other Members"? Am I missing something? Are early sales only going to be a membership magic thing? Because they surely won't tell white cards that purchased at a true that they must wait for a second booking window...