Originally Posted by
EU-US
3. Buy a Y ticket for my gf and once on the flight, move her to the empty seat in business (which I've paid for but my ex will obviously be a no-show if the ticket isn't cancelled in advance, so the seat should be empty. I just don't know if flight attendants will allow this or not.
I can only speculate on the other ones, but this one 100% will not work, AFAIK, on
any airline. That "empty" seat in business won't be empty for long (upgrade, nonrev, etc.), and even if it was, it wouldn't be yours to take. The ticket & seat are forfeited once the ex fails to show, so even though you've paid for it, it no longer belongs to you (or your ex).
As for the name change/refund, check the fare rules. If it can be refunded (not travel credit) with a fee, take that option. It'll probably be a few hundred bucks per ticket. You can also call up and ask, "hey, we divorced and the ex is no longer traveling. What are my options?" It may involve sending in copies of your papers, but it's worth a shot.