We purchased ours separately and will advise operator we have two accounts when we book. Don't forget to allow for 7.5% USA tax and the current USD/AUD exchange rate when buying miles.
Two award seats in J from OZ to USA return is 220USDM in total - see
award chart.
Award seats out of OZ ports in J to USA very hard to find even if booking 330 days out, but most here would find award seats on at least 2 other Oneworld sites like BA, AA, JL latter are free to join) or QF or use
KVS tool first before calling, if no luck with operator hang up and call again (they vary).
You could consider as many do going to USA via Hong Kong, a fantastic vibrant safe city.
The USA airlines mile deals are sure worth it to put the hard yards in and be flexible on dates to find J/F flights when your paying 1/3 or less the J price.