Return TPAC and return TATL on one booking?
Looks like the following is bookable on the AP website:
YHZ-YUL-YVR-SYD
SYD-YVR-YUL-LHR
LHR-YHZ
The MPM for YHZ-SYD could allow a return trip across the Atlantic after a return trip across the Pacific.
160,000 points all in AC J, YQ is $1,800