Being so close to the cruise (only a few days out) it is probably the final word since everyone is paid in full and there will be few cancellations.
But, it can't hurt to keep calling. It sounds as if you have the space in your cabins but the problem is probably that the lifeboat station for your cabins is at capacity or the kids club is. So if by some chance someone who shares your lifeboat stations cancels in the next few days, that might work to your favor.
But that being said, I'm not sure what the rules are about adding a pax so close to the cruise. Someone else might be able to answer.
Have fun on the 9th!