PAX
Liam548 quote
"me and my brother are both at the same stages of our PPLs, (Ex 12/13). Earlier on I used to sit in on his lessons and him on mine, I have put Passenger and the exercises he was learning in the remarks section. I did this as although not in control myself I am also learning, and the instructor is in the front teaching."
But buddying up with someone while they line and vice versa is a good way to accelerate the process even if you can't log it as flight time. You might call it elevated groundschool though
You can do the same when training for your IR and then log it as safety pilot (assuming VMC etc) and if the instructor does not mind