Book on the QF/QFF website.
You will earn the most QFF by having the QF3xx code, rather than the AY code,
If I were doing it, I would do the QF/QFF booking, and earn the most QFF SC for now.
Then, when QF starts its own flights, without premY, decide then, but keep with QF if you have to fly Y/subclass of Y.
Do not do DXB - BKK, as there is most likely no QF code on that EK flight, you will earn little QFF points on an EK flight #.
JL SYD - NRT/HND - BKK will be ok, as they are in OW, you will earn.
QF have their QFF points and QFF SC calculator.
The aim is to get to QFF SG, but at 4 flights in subclass of Y/or full Y, I don't think you will reach SG, maybe PS and a half.
PS as we call it, only gets one visit to a QF int lounge, but SG will give you a years of visit.
The idea is to get as much flights as you can with a QF flight number, better still if its on a QF plane too, but AY's service, with a QF flight number, can do, and EK with a QF flight number can do too.
Mind you, SQ is a great airline, but to get status, as I mention, you have to fly a lot, in a premium cabin all the time!
QF flex Y will earn more than disc Y, but in the end, its up to your finances, and who is paying.
QFF points need activity every 18 months, which for us in Aust is easy.
SQ miles have a life of 3 years, and they are strict about it, they have been extending the points live/life, but maybe in a few months, they will start bringing back the 3 years life of KF miles.
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Once the AY flights with the QF flight number stops, you can still earn QFF points flying AY, but it will be less.
What QF wants, is you to fly either BNE - SYD - BKK, or BNE - SIN and then SIN - BKK with 3K.
Check the codes, there is a part of AFF that breaks down the meaning of the abbreviations.
Sorry for the waffly.