This isn't a bad idea at all. Knowledge is power, right?

I can think of a couple of ways that they could leave messages around the park, but... [If she says them right here, then anyone would know and the VIPs could make fakes. A dilemma.]

After a couple of nights, they'd have a handful of people that they would know if it's safe to talk to or not. They could make allies of the people who they know can be trusted, somehow.