I politely commented that this seemed a little odd, since couldn't I go to a kiosk upon park entry and book an available FP+ anytime between 7-10pm? He simply repeated that there was no FP+ for this event. It left me scratching my head, but I didn't push it any further.
I suspect the CM was misinformed, as the news about this event broke early and I'm guessing they weren't prepared to field too many questions.
I suppose there probably aren't very many people with multiple tickets in
MDE at the same time. My situation is complicated by having a short trip scheduled in late May with my middle DD and so I hope the system knows which tickets/FP+ for which trip and which person, but I will probably stop at
Guest Relations on our first day to have them doublecheck everything and verify that entitlements are being pulled from the right tickets. Anyway, I digress... Point being, the system DID let me book FP+ for the event date. Now the odd thing (to me), is that it was offering me FP+ options throughout the day -- I would have thought they'd have the system offer only FP+ beginning at 7pm for people booking FP+ through the event tickets, but maybe they just didn't bother to do that and figure anyone who books FP+ before they can actually get into the park will have to forfeit them. The system definitely stopped offering FP+ at 10pm (the latest one I booked was 7DMT with a window of 9:25-10:00), so I'm fairly confident the CM was correct that there would not be FP+ at all during the event.
Sorry this got so long. Hopefully it's somewhat helpful to someone...!