Here's the deal....it's the difference between bookable categories and requests that causes the confusion.
For example, bunk bed rooms at WL are a bookable category. Let's say there are 25 bunk bed rooms at the resort (just a random number, I have no idea how many there are). When you call and book one of those rooms for this Thursday, the system removes a room from the total available. Now there are 24 available for Thursday. When all of the rooms are booked for that day, the next person who calls is out of luck - they are told that there are no more bunk bed rooms available for Thursday, and can't book one.
Requests are a whole 'nother thing. If there are 200 connecting room pairs at Pop (again, just a number), there's nothing in the system to prevent 210 guests from requesting them for the same night. 10 guests aren't going to get connecting rooms.
Now, I have no idea if they prioritize requests by family configuration, number of adults, etc. Maybe they do, maybe they don't, but if you get there and all of the connecting rooms are occupied......your 'guaranteed' room ain't so guaranteed.
The bottom line is, they will certainly try their best to accommodate your requests, and most people who request connecting rooms get them. But it is possible that you will get non-connecting rooms.
If it's absolutely imperative that your entire family be together in the same room or connected rooms, the only way you can truly guarantee it is by booking a single room that holds your entire family.