We are going on a Carnival cruise later this year and have booked two rooms. How difficult would it be to change which person is in each room after we have booked and paid for the cruise? We just want to rearrange the room assignments. We got a better deal booking the way we did but this is not how we want to spend the cruise. Should we try to take care of this at the dock or just wait til we get onboard and go to the pursers office? Any problems doing this?