Originally Posted by
Often1
The GA for the flight can add you until the flight is closed. "Closed" does not mean the door, but rather that the paperwork is transmitted to the dispatcher to calculate weight & balance.
If there is a delay and the GA is willing to add you while the aircraft is sitting at the gate and the flight is not closed, the GA can certainly do it.
But, it is completely the agent's discretion. It is going to be low on the agent's list of priorities as delaying the push because the GA has boarded a passenger and loused up the passenger count requiring both the Captain and dispatch to recalculate weight & balance is not the kind of thing which endears GA's to their employer.
Final weight and balance details and the associated final "paperwork" for domestic flights are transmitted electronically to the flight deck while the plane is taxing out. The paperwork given to the FAs when the door closes is for their use and doesn't have to reflect the final status of the flight. With the increasing use of the FA smartphones I wouldn't be surprised if the hard copy paperwork goes away. I think international flights have more strict requirements for some destinations.