Similar situation.,.. we had three Platinum members in one cabin and we decided to let our son bring a friend. Only problem was that our current stateroom only slept three so we remained in our cabin and moved our son and his friend into an inside guarantee....at prevailing rates AND it's less expensive for the third/fourth passenger - so we had to pay more to move him AND I had booked all of our Port Adventures and and Palo and he was dropped from all of them because it was "a new reservation" to
DCL. Because we added the friend so much later, now there is no availability for the extra person (friend) and my son no longer has anything booked. However, because my son is Platinum at least he'll still get the onboard gift (which isn't a big deal to us) and he still gets dinner at Palo's if they squeeze him in somewhere.