Originally Posted by
Cosgr
Also, if you don't have a confirmation number, you can check in using your name at a kiosk and switch your seats there. I've done this a few times.
Depending on the gate agent, they will look out for you. I was originally assigned to DH in last row seat next to someone on a 200. When I got to the gate, the gate agent moved me to the first row with an empty seat next to me. Be nice to the gate agents, they will be nice to you.