From what I understand at the sanctum, pretty much everyone always plays every round. Not sure how Chad handled things at his, @djreddog, but yeah if they leave for a bit, de activate, then re activate when they return. If they drop out all together, not sure how that would work for TGP. I would just keep track of all that stuff and let the IFPA know What happened.
I’ll take a stab at how they would handle it. You’ll get 2x TGP credit for all rounds where more than half the groups are 4 player groups. As long as a player has played in 50% of the rounds, they will count towards TGP.