I spoke with the Air India office in Chicago this morning and my son's booking has been updated to remove the fraudulent API and Frequent Flyer info. They didn't know how/when it was added but patiently helped rectify the situation.

I don't think it's a UA agent, there was total chaos at the O'Hare AI counter when my son was flying out on the 7th, flight delayed 13 hours from noon to 1 am, and a couple hundred passengers waiting to check in plus plus dealing with missed connections in Delhi, so my guess is it happened in that chaos. Ticket was a paid J and my son usually keeps his BP as a souvenir.

im.daniel - If this happens on the inbound, I will follow in your steps and call UA, and mention the fraudulent AC account. My family has never flown Air Canada nor do any of us have AC frequent flyer numbers so this whole thing is truly bizarre. I also kept screenshots of the AC frequent flyer number as proof.