Other passenger(s) are certainly OK, but I think you're pushing it a bit with 3 extra, and even more so if you try to specify a larger vehicle. I would also recommend one drop off point and let one party do the last 5 minutes under their own steam.
There are numbers in the OP, but I'm not sure if these are for the Chauffeur Co. or for Emirates. Contacting the Chauffeur Co. would be the way to go IMO, if you do try, I've never had a call you for an airport pick up - they know where you'll be and when already.