You could just force everyone to use their initials for carts. I'm interviewing for the FOTL as well and it was something I suggested since its nearly impossible to find out who is using a cart since no one ever responds to that call and by then the order is late. I made a list of everyone that is actually in fulfillment and those that help out frequently, and printed out the subcart using backroom location management and put them on a giftcard, laminated them, and then put them in badge holders that HR has. For example if John Smith was a fulfillment person, their cart would be SHPJS. Obviously if you are in dire need and have everyone in gm jump in you won't know unless you have them call out the cart they are using when they start so you can remember it and you also need to find a way if multiple people have the same initials. We've been doing it for a couple weeks and people will actually answer if you call them out by name instead of calling 20+ times about who has cart zj.