Just pulled up our flights on the TK website. There was a red flag indicating "missing details." It wanted our identification info. I entered our passport info in the blanks, clicked save, then got an error message saying that they could not accept our private information because the reservation was not made on the TK site. (UA.com and 016 stock). It then says to contact the agent from whom we bought the tickets.

We did not use an agent. We booked online at UA.com. I'd really like to get this accomplished ahead of time and not at the airport on departure day. Any ideas?