Hi all. I am trying to create the trust game in the studio with the design that for the first half of the game, half of the participants will play sender or receiver. Then in the second half, they will switch roles.

I want them to be randomly matched every round, but to keep their role (id_in_group) for the first 2/4 rounds then switch role for the last 2/4 rounds. I have been trying everything but cannot get it right. Please help :(