In my first year at my previous company, another coordinator and I shared responsibility for event logistics, and we kept stepping on each other — I'd confirm a vendor she'd already renegotiated, she'd change a layout I'd finalized. It came to a head when a double-booking embarrassed us both in front of our manager, and honestly, at that point we were barely speaking.
I asked her to grab coffee and opened by owning my half: I'd been treating the shared checklist as mine. It turned out she'd read my constant confirmations as me not trusting her work, which wasn't how I'd meant them at all. The actual problem was that nobody had ever split the ownership clearly.
We divided the checklist by vendor category, set a fifteen-minute Monday sync, and the overlap problems stopped. By the next event season we requested to be paired together — the sync habit we invented ended up being adopted by the whole team.