Thank you, mahdnc. Oddly, it is the third person in the stateroom with the higher fare. The second one was the lowest. So I think if we were able to move one person, we would then have a 2nd guest fare twice (one in each cabin); lower than the third person.
We would be paying thousands more, of course, for the new reserved guest and additional cabin, which of course is fine. I just won't pay a penalty deposit to do so. We'll just skip that booking and stick with what we have and not pay for the extra cabin and passenger. It saves us quite a bit of money overall of course but a shame to not be able to have this person join us without incurring a lost deposit for adding another guest and cabin to our group.
I spent about 30 minutes on the phone with Celebrity yesterday trying to get an answer. They finally told me I'd need to call back today and gave me a number. I may or may not bother. It seems complicated at the very least. We have until this Wednesday for complete deposit refunds but they seem so confused about this situation that I'm just afraid to mess with it.