The answer I think is it depends on where you're sailing from. Skipper's Club in Miami has a seperate lounge for check in, and they escort you onto the ship as soon as boarding is allowed (if you are there that early).
There they have allowed us to check in other members of our family who were not in Cat11 or 12 cabins, and they've boarded with us.
In other ports of debarkation, where they have no lounge..... like Ft Lauderdale, Skipper's Club didnt seem to mean much.