Brian Schear was blatantly trying to cheat the system. You just cannot give the ticket to another person. You have to cancel the first ticket for your elder son and buy a new sear for your toddler. Everybody knows that in this post-911 era. FAA regs won’t allow a passenger not on the manifest to fly. The airline cannot choose which regs to enforce and which to ignore.
How in the world did they get the toddler past security and onto the plane in the first place? His name did not match the passenger manifest. Maybe the similarity of the kids’ first names fooled the TSA and airline people - Mason and Grayson. It’s another breakdown in security.
When the 18 year old didn't show, the airline checked and found the toddler not on the parents lap....but in the seat vacated by the 18 year old. They were NOT entitled to use the 18 year olds seat. I'm inclined to say....clever?? or fraud because I'm sure the 18year old used the money from the vacated seat for the earlier flight.
At some point, the parents should have actually mentioned it to the attendant before boarding that the 18 year old wasn't coming.