I’ve covered this before here, which should be enough to get a system working 
I just had another look at our companion repo and realised it may be possible to set the cameras up independently by creating multiple param files that specify the different ports, and just starting separate screen sessions for them in .companion.rc instead of modifying the streamer.py and start_video.sh scripts. I believe that shouldn’t be overly difficult to get working, but I’ll try to have a play some time this week if I can.