Originally Posted by
matthandy
A child cannot be allocated an exit row seat, however, there is nothing to stop a parent booking it and then once the seat belt sign is off, swapping with the child during the flight. Once the descent has started, you'd have to move back.
The doors cannot be opened in flight anyway, so I don't see any practical reason as to why you wouldn't be able to do this.
If there was an emergency, the cabin crew would have a lot to do. It would not be practical for them to be focused on having the children switched out of exit row seats and adults put back in. The plane could also be flying uncontrollably, making this even more difficult.