It will be more difficult to make changes to ALL 5 rooms, so getting as much information into the system ahead of time is key...
As long as that is in the system and the assignor (and automated part) knows that, then that is your best shot at starting out in a good place. If you go to the front desk to check in, if ALL the rooms aren't ready and you REALLY want them to stay with your preferences, it will be harder for them to move things around right there. You ARE able to explain to them any nuances that you may have to see if they CAN change things around if you don't like the location of already confirmed rooms, but it's still way better to have all the requests ahead of time than waiting to get them working on it that day. I agree that the "front desk" is more for tweaking than doing "normal check in" things, as they don't have ALL AUTHORITY to do all the things, especially since most room assigning is basically a puzzle.
Though normally when we have 2 people charging different cards on our MB+, we need to go to the FD to double check that anyways hahaha
But I sometimes wonder if I would be a the resort at checkin time if it would be better to go to the desk to see if the room is ready rather than waiting for the room ready text which has come at like 9pm sometimes (we've been at the parks, so no big deal, it's probably helpful for them to be able to switch rooms for people who are ACTUALLY waiting at the resort). From my time working in a hotel, we were surely attempting to get people in front of our faces into ready rooms after the check in time.....but we don't have any particular needs....
All that said, do all the things you can do in advance, and then ask for help at the FD (which you might need anyway with charging between many people) if needed.