You could try Air France around those dates, as they will do you a regional connection to CDG
, then CDG
on their 777-300ER. You should then be able to get a Qantas flight to SYD
as they have a code share agreement with them.
I'm off to Melbourne for a month at the start of January, and I was given the option of going from SIN
, and then taking a regional connection with Qantas.
Hope this helps, and I'm paying £810 all in. It was the best deal I could get considering it is still a high season booking.
Hope you get something.