I'm not sure if you guys may not be aware, but a fake check or a fake bill will be found and dealt with on the day of its donation at any assembly or convention.
Each event has a specified location on premisis that is locked down and only very few allows inside. This room is where all of the money ends up and is counted by several people and added up. During this time they watch for fakes. (at least that's what I've been told, I've seen the places where they count because I escorted someone there as an attendant.)
even if not found there, a bank would notice it and alert the corporation and it'd be dealt with.