Originally Posted by
Stgermainparis
And to piggyback on this: see if you can simply do a “change flight” on the UA website. Not all airlines offer that but it’s a nice feature bc means you don’t have to cancel, get back miles, rebook.
On the contrary, if you have sufficient miles and all necessary flights are available, I highly recommend the book-then-cancel approach. Using “change flights” can put you into a situation where you end up without a seat. It doesn’t happen every time, but it happens frequently enough that it’s a legitimate worry. Specifically, what happens is that UA sometimes does not push the updated ticket number through to the partner airline. When they revalidate that record at some future time, it’ll find the old ticket which is marked as having been exchanged for something else, and it’ll release the confirmed space. I’ve had this happen to me personally, and it happens with some frequency on the board.