Have 1M VFF points and approx 200K QF but there didn't seem to be any award availability to use those VA points on SAA or even SIN. Generally we feel we get the best value from our points on RTW fares so I was thinking it would be a bit of a waste to burn them on a trip that's only 7 - 10 days long. Would have been much better if we had been given more warning of the date but they have work friends coming from multiple countries so they just decided the Xmas - NY break would suit most people best.
You could use QF points to fly on CX749 HKG/JNB 2350/0645+1 which has award seats in both PE & J ex HKG on Tue 27 Dec for 75K & 92K respectively plus taxes of HKD330.00 (approx AUD56.00) which are the same regardless of class travelled. There is only PE available on Mon 26 Dec CX749.
You could always purchase a separate ticket on CX MEL/HKG/MEL and even with the new OW interlining rules CX could still through check you from MEL to JNB on two separate tickets as the first is a paid ticket and the second an award ticket.
I can't see any award availability for the return flights. However, a paid SQ J ticket from JNB to MEL (via SIN) costs under $2,400 each. That's with an A350 from JNB-SIN and an A380 from SIN to MEL. Emirates is also around that price, but the flying time would be a little bit longer.
That's a great idea so the OP could always nest the HKG/MEL leg of the paid ticket and choose a date for a separate trip to HKG then just do a one way award flight MEL/HKG to position.
To summarise:
South Africa trip Dec/Jan
MEL/HKG 26 or 27 Dec outbound leg of a paid ticket MEL/HKG/MEL in whY
HKG/JNB 26 or 27 Dec one way Classic/Partner award using QF points to travel on CX in PE or J
JNB/SIN/MEL one way paid J fare on SQ as per Mattg's suggestion above
Separate HKG trip future date
MEL/HKG tbc one way award to position eg wedding anniversary, milestone birthday
HKG/MEL tbc return leg of MEL/HKG/MEL ticket (outbound flight would be 26 or 27 Dec) you would need to know the date at the time of booking to minimise any change fees etc.
The reason I suggested purchasing a return MEL/HKG/MEL ticket on CX is that there may not be a lot of difference for a one way paid fare. If you didn't mind flying whY on the shorter flights MEL/HKG vv then do the long haul ex HKG/JNB in PE or J.