Thanks for that. At 1am this morning I was waiting on hold to Qantas again and discovered the BA executive club search tool, which revealed a little bit more availability than I'd found on Qantas' site. However, the taxes/fees/surcharges seemed incredible e.g. JFK-BOS-LHR $3000+, LHR-HND $2180 and MAD-DOH-CMB $1500 (all AUD). Does this sound correct? And might availability on the trip home still open up with some Oneworld carries, or is it all 'done' as it's only 9 months away?IB, BA and AY should fly to Split (SPU) from MAD, LHR or HEL respectively for your Croatia leg.
I have previously seen 4x J on AY, CX and QR; it all depends on how you want to get home. Try all of the routes from HEL to Asia, and similarly legs to all of the different Australian ports from wherever you find availability in Asia - QR availability can be easier into PER, for example.
Your boys are going to be absolutely spoilt!