Thanks for the reply and info re DOH-MEL QSuites. Happy to report a successful booking today for the first section below (2 x J) for March/April 23 as a Silver member. The final Finnair leg was able to be booked for 24 April even though the latest date available in the initial Qantas mulitcity date search was 17 April. Using "all dates flexible", at the second screen there was an additional week available for this last leg. I was pretty keen to get on QF for SYD-HND and knew it was touch and go re availability while waiting for the last AY leg to open (6 weeks after the QF flight). Super happy right now. Thanks to everyone who contributes to this thread for all the great tips and information! Now to prepare myself for phoning Qantas to add the additional legs in a few monthsI can't see any problems with either of your options, Rach1616.
I guess you threw in the DOH-ADL-MEL to get the QSuites on the DOH-ADL flight but QR is now flying the A350-1000 (A351) on the DOH-MEL route and all of them have QSuites so the direct flight to MEL will save you an ADL transit. Award availability in J should be quite easy to book provided you don't leave it too late.

Locked and loaded:
MEL-SYD-HND-KIX (QF and JL) stop 1
KIX-NRT surface sector
NRT-YVR (JL) stop 2
YVR-JFK surface sector
JFK-HEL-LIS (AY) stop 3