There are lots of problems with this itinerary. I think you'd be more successful on *A (albeit fares are higher), or have to take quite a bit out to make it work.

There are no IST-CAI flights. You would have to transit through AMM (Amman on Royal Jordanian) or MAD (Madrid on Iberian).

There are no CAI-EBB or DAR flights. The only way to get there on OW is on BA, but as you originated in LHR you cannot transfer back through there. One way to resolve this is to start your ticket somewhere else, however fare is likely higher and you already have too many sectors.

There are no EBB-JNB or DAR-JNB flights. On oneworld you will have to take a surface segment and find other means of travel for this bit.

There are no JNB-BOM flights. You could go via HKG (Hong Kong on Cathay Pacific).

There are no oneworld HAN-SYD flights, nor CHC-NAN, nor NAN-AKL.