The good news is that you will love VIP Check In in Miami.
They have a completely separate room with lots of comfy couches to relax while you wait to board.
A lady will come in and gather everyone together to take them on board.
The BAD news is that your friends will not be allowed to board with you if they are not VIP (Platinum or in a Suite).
We watched time and time again as people tried this and the Miami Carnival Reps said no way...not even for one person.
The only exception is IF a family with children (especially that are minors) have booked TWO cabins....a Suite and a lesser cabin for the kids. In that case, they all go through VIP.