My ressy last March indicated our connecting rooms were guaranteed
And I've never understood why there's that disconnect between the reservation paperwork and what's possible for the resort to do.
As it stands now, I don't believe it's possible for them to guarantee connecting rooms, for one simple reason - there's no way to reserve them. They're not a bookable category.
For instance, if you call and say "I want a bunkbed room at WL", the system reserves a bunkbed room for you. It knows how many bunkbed rooms there are at WL, and when all of them are reserved for a certain day, the system will not allow any more to be booked.
It doesn't work that way for connecting rooms. It can be noted as a request, but the system doesn't say, "OK, I've got 152 connecting room pairs at this resort, and Lynne just reserved one, so now only 151 are left." So in theory, they could have 420 guests request connecting rooms at a resort where there are only 400 connecting room pairs. 20 of those 420 people who requested it aren't going to get it.
From what I understand, they really do treat connecting room requests as a priority when assigning rooms. They'll certainly try their best to get you into a connecting room, and the vast majority of people who request them do get them. But it's never a guarantee, and some people don't get that request granted.
If it's critically important that your party can't be separated, the only way to guarantee that you'll be together is to book a single room that holds your entire group. If one of your kids is under 3, then you can get a family suite at AoA or ASMu. If your kids are all older than three, then you'd need a two-bedroom villa at a deluxe villa (DVC) resort.