I wasn't sure if it might be frowned upon, but we do this (post cancellations) with hard-to-find reservations on the Tripadvisor forum where I am a DE. ( Hard to find as in Grand Canyon Phantom Ranch, nearly impossible to book).

Checked again just now and they are still available. Brisbane in January, what is not to like?

I canceled because I was able to replace them with seats booked with my AS miles which cost far less---but cannot be booked 355 days in advance like Avios bookings. I just got lucky with the AS miles.