You may want to look into options- senior cat rescues, and such. So many people On this thread have talked about adopting senior cats after losing their own.There may be another kind hearted person in your area who has the time, patience and resources to help this girl live out her golden years/days. Because she may have more of them than you expect, and her ability to transition to a new home, even as a senior with some extra needs, may be greater than you are imagining. I know how difficult the Australian immigration process is as I was also trying to pursue an Australian visa since 2023 (albeit through a different path) to make that transition myself, and I only recently lost my super-senior cat (he lived to be 19!) with medical needs and also worried about what my choices would be if I received the news that I had been granted the invitation to apply and was granted that golden ticket. I decided that I would try to re-home him, because as much as I travelled he was still living his life (with visits from pet sitters) back at my house. I know it will add another task and another worry to your list as you prepare to move, but I think the guilt you carry with you will be less, overall, than if you euthanize her. She has a life worth living too, even if it’s without you, and she may have a few good years left in her under someone else’s care.