After searching this forum and other googling, I found a good amount of information on trying to upgrade BA and QF segments on RTW tickets but the information was generally old and possibly stale. Thus, I'm asking for confirmation and/or recent experience. Here are my circumstances:

Just booked DONE4 ex-JNB with AA JNB (Mindpearl). Segments I would consider upgrading if possible:

JNB-LHR (BA flight operated by BA)
LHR-ORD (AA codeshare flight operated by BA)
LAX-MEL (AA codeshare flight operated by QF)
SYD-JNB (QF flight operated by QF)

From reading the older threads in this forum, it seems I am out of luck on the BA segments; as people have indicated that the ticket must be purchased through BA in order to upgrade with Avios. With respect to QF, I have found some discussion that indicates it may be possible using QF miles.

Can anyone confirm and/or share recent history with trying to upgrade BA or QF segments on a DONEX ticket? Preferably one booked by AA?