Originally Posted by
Kacee
On a UA ticket, you can SDC via the App (assuming availability) as soon as you scan your BP to board the first flight. On an NH ticket, I would assume same, but have never tried.
SDC does not work on an NH ticket, because UA can't reissue the ticket.
I tried to SDC a non-UA ticket once. I ended up with a ticket that was out of sync with no way to restore it. I called UA and I got lucky -- they were able to restore my original itinerary.
Standby on non-UA tickets -- not a problem.
SDC on non-UA tickets -- don't try it, at least prior to the day of travel. It might work
on the day of travel, because UA can take over the ticket at that point, but even then I wouldn't try it from the app. Upon entering the US, at the re-check counter (where you'll need to go if you have checked luggage anyway), just say "my flight isn't for 8 hours, but I see there's another one in two hours. I don't suppose you could put me on that?" and see how things go.