Hello,
We just got back, and my sons started pin trading this vacation and had a ball. The only rules we observed with the CMs was that if the CM wore a green lanyard, they could only trade with children 11 and under, no adults. The CMs with black lanyards could trade with everybody. If they did not have the pin you wanted to give them from your lanyard, they had to trade for anything you wanted on their lanyard.
It was a great way for my sons to meet some CMs. We didn't trade with non-CMs as we were novices.