Here are a few critical things for the rear diff service.
Oil Capacities:
Center SAF XO: 0.95L
Left SAF Carbon Mod: 0.54L
Right SAF Carbon Mod: 0.58L
I used Liqui Moly 2048 in the center section as the BMW branded fluid is impossible to find and there is nothing special about it anyway. For the left and right chambers, use genuine Castrol SAF carbon mod. This is used by a lot of different car makers and sold in their branded bottles. I found the AC Delco branded bottles to be the least expensive. Look for AC Delco 92184900 which is a Holden part number.
Make sure you have a way to measure the fluid you are putting in,
this is a good option
To reset the diff in ISTA, you need to run the "QMVH Oil Change" service function.
If you are looking for different options to source the Castrol SAF Carbon Mod fluid
many OE part numbers are listed here