I've had it happen coming out of BOS. Two kids ended up boarding the wrong Chicago bound flight on UA (the one flight was boarding at the latter flights boarding time due to delays). The kids went to the back of the bus, only to discover that row 32 did not exist. At this point an FA caught them and sent them back to the other plane. How do these people board the flight. Doesn't the GA scan/look at the BP?

W