Serfty is probably right with 1 to 4 but being right does not necessarily mean you get what you are entitled to, and minutes before departure is not the time to argue the toss with an adamant supervisor who has the power to kick you out. I would only book number 2. There is no way I'd risk numbers 1,3,4 or any combination other than a plain vanilla Oz-LAX-JFK or JFK-LAX-Oz. Not worth the hassle, IMO.