A practical question for those who are more familiar with this topic:

If I book a LONE4 ex-Oz, can I start with an AA codeshare flight SYD-MEL, stopover in MEL and then take a QF flight (not the AA codeshare) to LAX?

On a simpler level, can you take the AA codeshare SYD-MEL and then (no stopover) take the QF flight MEL-LAX?