She could reticket as a AONE4 (pay fare difference, change fee), loses the benefit of F for the flights already taken and only benefits for LAX-SYD and SYD-JNB in any case (already in F BOS-ORD-SFO-LAX and no F SYD-ADL-SYD).
If she has enough QFF miles (ie lots) and there is availability then yes can upgrade on LAX-SYD and SYD-JNB.