As an update, we managed to get the outbound flights we wanted:
QR905 - MEL > DOH & QR037 - DOH > CDG
Now the nervous waiting game begins again whilst waiting for the dates to open up for the inbound... we were thinking we'd like to try an EK product on the way home, but as they're released ~3 weeks after the QR seats open up, we'll likely grab QR when (if) they become available. We will be finishing our trip in Munich (Oktoberfest) so have plenty of options "close by" to start the journey home from (on QR/EK):
MUN, FRA, ZRH, DUS, HAM, VIE, PRG, TXL, CDG, MXP...