I'd just add that while a QR J itinerary doesn't fall within budget, that it would boost the two passengers quite close to BA Silver. With a positioning flight presumably on BA, you'd mostly need two more segments with BA to get Silver (may have to book the economy fare class that earns 10TP if there's no other flight activity).
If budget is strict or status of no interest, I would burn the 241 to fly in WTP to, well, pretty much any eastern hub. KUL, CMB, HKG, SIN, whatever is cheapest to depart from. Then a paid PE/Biz ticket to get to Sydney.
There's also the option of buying avios to get a 241 WTP redemption to SYD but I can only imagine those are very sparse.