Thanks for all the info guys. I called the AA RTW desk AGAIN. and this time I got a different answer.
Essentially I want to start in BBK so my schedule will be as follows
BKK-SYD (on QF2)
SYD-LHR (either on BA10, QF1, QF29, or QF31 - all same plane through service but transit in Asia, either Bkk, Sin or Hkg)
LHR-JFK (on AA131 - TransAtlantic)
** Various segments in US**
JFK-BKK (CX - TransPacific) end...

The guy I spoke to at AA RTW said that SYD-LHR with transit in Asia is do-able.... but the woman I spoke to earlier said it was not. So now I'm even more confused...