Go Star Alliance the entire trip. As you mentioned the only direct flights are on the BJS BRU route and that too is not a non stop either.
Brussels- Frankfurt- Beijing on Lufthansa - Daily connections
Leaving arnd 3 PM from BRU reaching Beijing 0830 next day with a 80 min transit at Frankfurt
Beijing - Seoul - Sydney on Asiana - Daily ex Wednesday
Leaving around 4 PM and reaching 7 Am next day with a 90 min transit.
Wednesday also connection possible but add another three hour transit time
Sydney Vienna Brussels - Austrian (from SYD on Lauda Air a/c)
Daily except Tuesday - 1700 SYD and 0900 arr Vienna next day
Cant get much better than these . All flights non stop except the SYD VIE whch routes via Kualumpur.