Thanks for you reply. Both flights are on the same ticket, so rescheduling both flights is a possibility. But through the JAL online booking site, it hasn't been possible to book any YVR-MEL flights for December and January for the last couple of months. Not sure if it's because of scheduling changes or full flights.
With JL773 cancelled, will JAL replace it with a different flight, or a cancellation is just a step in the process of rescheduling, or it will just be a void?