New experience for me on a flight from LIS to FCO...

Was sitting in 1C on an A320 and before takeoff a large group of kids (probably ages 12-14) in matching shirts were boarding. Flight crew let the kids look around the cockpit and take pictures, normal enough. Then they put down the jumpseats and invited a couple of kids to sit in the cockpit. Door was closed and we pushed back from the gate. They sat in the cockpit the entire flight and came out after landing.

Obviously everything turned out fine but surely this cannot be allowed by any safety policy?