How is starting order in Meetups decided?

At our club we have a League with about 40 users (75 unique users) every week. Because the club functionality isn’t rolled out to us, we use the Meetup-functionality. Unfortunately this means that the finish of each participant is different. This can be as much difference as 200 meters!!!

Big question is: how the starting order of those Meetups is decided? Because this starting order seems to influence the placement of the finish for the participants.

I rode a Meetup yesterday, and I believe that the order is decided on when you join the Meetup. That is, the last one to join is at the front of the group, and has the least distance to ride.

I don’t think it’s based on join order. I do two Meetups every week, and the placing seems pretty random to me.