They had put this white picket fencing around the stage - tall enough to stop them from swarming the stage, but not actual stage fencing. Toddlers after all. But these kids would grab it and shake it violently, and since it was wooden and heavy, would fall either on them or over.

We'd also have to escort Barney and crew around the convention, like his secret service or something.

They had handlers, like caretakers or whatever that would like 'take care of the little crowd' so the parents could sit in the back. But obviously, when that "Barney is a dinosaur of our imagination" song starts, it's like Michael Jackson coming on stage, these kids just let loose and start throwing themselves on the stage even running around the side to the backstage and running up on stage.