The oneworld flights I have booked are all part of the CMB-JFK mistake fares. These flights I have posted are indeed one ways, with flights to BNE/SYD before and flights onwards from Europe.

I found a few more orphan LA flights that will bring me up to saphire on BA, but not on QF, so have signed up for BA and will collect with them.

Thanks, as always, for the advice.