You would need to use AA miles for that and go thru HKG on CX if you want to go to JNB but avoid the horrendous BA Fuel Surcharge.
Go YYZ-HKG-JNB, or YVR-HKG-JNB depends on which coast you are in Canada. Or connect in US and go CX from JFK/ORD/SFO/LAX. It will be 2 awards but you get to stopover at HKG.