Yep, might change ZQN-CHC into the same airport to avoid the surface segment, though I'm not sure where I would use that freed up segment, given that I've already used up the max allowance for flights within Europe and Asia, and have time constraints surrounding how long I will stay in Oceania. Perhaps I could make a detour via NAN to maximise points earn, will have a deeper look. Also wish to try the new Aria Suites which only fly to SYD and MEL currently, hence not taking the NZ-HKG CX flights.

I believe the codeshares all exist, but the only thing I don't know is if I actually have this freedom to nitpick the codeshares for every flight I want, or if there are some married segment logic or requirement to link it with a prime flight of that carrier. Not sure I understand your example on the SYD-HKG routing, as your example of the CX flight shows a BA code like I have in my itinerary. Same way I wrote AA between HKG and SIN, which is obviously operated by CX. The reason for this is that AA, BA, IB codes earn double the tier points vs CX, QF, JL, etc. on AY, so I'm trying to pick these codes where possible. Not sure if this has YQ/YR implications, especially with BA's reputation of high surcharges on their own flights, do these apply to codeshares too? This

https://www.flyertalk.com/forum/37292353-post1122.html
Saw this post mentioning QR-issued tickets only have YQ/YR levied on QR and BA sectors, unsure if that's universally applicable or if I've misunderstood.