It does not have to be a message either. There are a lot of advantages to using children as spies, the reason mostly is they can fly under the radar and just run around the streets pretending to play soccer or whatever and eavesdrop on everyone's conversation, most people are disarmed around children and don't think much of it. And yes, children have been used as spies and even as soldiers in many many many conflicts. I even remember a couple of stories from Iraq about how American soldiers would befriend kids in neighborhoods and give them candy and toys and stuff and ask them to report anything they see. It is informal but that is still a form of spying.
