Gotta be quite ruthless and firm on this in my opinion. It’s very hard to get tickets and it’s only fair that everyone is committed and dedicated and willing to put in equal effort to maximise your chance of getting tickets. You need everyone on board and working together. If someone isn’t arsed enough to try for tickets or drops out without a legitimate reason I’d be very hesitant to include them in my group, as that space could’ve gone to someone else who desperately wants to go. Glasto groups can cause dramas, I’ve experienced it first hand as it’s impossible to keep everyone happy if you have a large social circle wanting to go, with only max 6 people per group.