I haven’t tried it lately but a couple years ago it would send it to the other passenger in the itinerary. I had a lot of follow up with United IT because I thought I might get a bug bounty, because when sent this revealed my personal info to the recipient. IT co formed it was a bug but didn’t award the bounty because that was not the kind of exposure of private information they were looking for help with. Still it was an interesting, repeatable problem.