I am looking to book MEL-SYD-HND-SYD in PEY and SYD-MEL in Y on a separate ticket because Qantas won't allow the final SYD-MEL leg on the companion fare sale, as long as the HND-SYD and SYD-MEL is on the same day would they honor the baggage allowance from the international leg to the SYD-MEL flight? The final SYD-MEL ticket would be booked using BA Avios points.