While the rooms may be blocked out that far in advance, nothing is set in stone until the guest has their room key in hand. On almost every occasion, I have been allowed to change my room assignment when checking in. so, lets say I have been assigned room number 2334. But when I get to the checkin desk, I find that that area is not a great one for me, so they allow me to choose a different room. I choose number 3445. Now, if that room had been assigned previously, that person would end up having a different room. And yes, I've been told, in person, by the resort checkin staff that they do it that way. Unless the resort is close to full, you have a good chance of being able to change your room assignment. So, it's sorta a 'guideline' when they assign you a room several days in advance.
Your best bet is to be sure the reservations are tied together. That's what we did when we had two families staying at POR years ago. We actually ended up in connecting rooms....perhaps a little too close in hindsight!!!
However, no way would I start calling the resort to make my requests. Just call whoever you booked your room with originally, and have them note your special requests/needs. You should be fine.