I'm taking my 18 year old niece to LA for as a graduation present, and I used miles to get her ticket, and purchased my own. So they're on 2 different itineraries, but the itineraries are identical and we're seated beside each other on all the flights. I was a little nervous about doing it this way, but I didn't have enough miles for both tickets, and I scoped the fights out in advance, and it looked like there were plenty of seats left on the flights for it to work out. So I redeemed miles for her flight first, and then bought my ticket, and it all worked out.

Is there any way to link these 2 itineraries so that UA will know we're flying together? Is there even any benefit to doing that? Like maybe if a flight would get cancelled for some reason? tls