Good point, can only be used on BA flights.

In that case, if the OP is wants to change flights once there, be ready that you might stuck in Australia for some time until 2 reward seats are available.

I was in MEL and pushing my bookings back, and looking at both MEL/SYD departures MAS had the most reward availability, BA had very little. In the end, the only flight I could get back in the week I flew there was 0 flights from MEL available on any carrier, and only the BA flight from SYD available, although I had to change to the 747 service in SIN, as the reward seat on the 2nd leg on BA16 got nabbed the hour before I called.