Originally Posted by yyzprincess

Code-Share has to have AC XXXX. FYI AC has no codeshare within Australia.

AC does not codeshare with: Qantas, Virgin Australia & JetStar.

When UA had tag flight SYD-MEL one could book that flight as Codeshare if I recall reading it on FT.

I have not flown AC to Australia since 2015.
Pre-2015, I found it was cheaper to book YYZ-SYD-YYZ & separate ticket to MEL where my Australian company is based. QF has excellent fares SYD-MEL-SYD in Business. As well if you have Avios points, excellent value for Business award. For coach only 4000 Avios.

BTW, I go to MEL every 6-8 weeks since 2003, happy to give you tips on what to see, do & places to eat.