Respectfully disagreeing with MarkLem, I do not mean this as a flame but merely my understadning is different, so I will post and hope that by doing so I help the OP get a differing viewpoint.
Everybody does not get a room number when making a reservation. There are GTY reservation categories, which I believe are not used until there is a near sellout of a particular category. Basically, GTY means you are guaranteed no lower than that category, and if none become available, you may be assigned a higher category stateroom. The subsequent availability comes from cancellations, changes, deposits not made by the end of the courtesy period.
Getting statements does not fix your stateroom, either. My doc's were printed with one stateroom number, the one I had been told a couple months earlier, and then I received an upgrade after the doc's were printed and was contacted by the TA to tell me to make the changes on the luggage tags that are part of the doc's. I have also seen others post on the Board that they learned of an upgrade when checking in at the terminal.
I'm sure everyone would agree--book the category stateroom you will like and you will never be disappointed. Your large group in 10 rooms, if you are all currently near each other, may cause
DCL to not consider y'all for upgrades because they might prefer to keep a group together if they booked together, and the opportunity for 10 rooms all being upgraded doesn't seem very high.