Originally Posted by tentseller

You need them all to be on your PNR/reservation. The maximum number was 9 on a PNR. When I was travelling with my NGO entourage we can all book into EC/C+ and they get my baggage allowance of three bags.

Since the C+ is now an upgrade you would need 4 available seats to upgrade to. They might not all open up at the same time and your entourage might be bypassed to the next in line.
Source DL DM CSR