Help with multi-segment AP award on SA
 

i am travelling MIa to JNB on 1/4/2017 ( not booked yet seats to be released on Friday by SA.

we are then going to Perth on 1/18/2017 also SA seats will be released end of January

we then will fly back to MIA 2/2 from SYD or BNE

so i am going to book 3 one ways because if a wait then 1/4 and 1/18 will be gone

i plan on having the last leg combined with the first 2 so am I going to have to pay 2 change fees or just 1

will the points be reduced when i combine all 3 sections?

Also will these exceed mileage restrictions?

and lastly can I return from say SIN or BKK as an open jaw?