Many of the boarding areas for wheelchairs are rather small and won't fit that many people. For some attractions, there are fairly small elevators that fit one or 2 people plus a wheelchair.
Also, for the seating areas in theaters, often there is a small number of seating spots next to the wheelchair spaces. We have already arrived for our Fastpass time for an attraction and had to wait for the next showing because 2 wheelchair parties with a lot of accompanying people had taken up all the companion seating (in a show that would normally hold 6 to 8 wheelchair parties). So, please wait in line together, but then meet up later.