I don't think you have the right fluids listed. Here is the documentation from ISTA/TIS:
Basic transmission, centre:
BMW Synthetics OSP 83 22 2 365 987 1000 ml
Variable ratio transmission left/right:
BMW final drive oil SAF-Carbon Mod. 83 12 0 445 832 3 x 500 ml
from here:
https://www.newtis.info/tisv2/a/en/f...-drive/1EYYaQR
And you will need 6 replacement drain plugs to do all 3 chambers, not two.
It is possible (and reasonable) to only change the oil in the center section as you point out in your documentation. It all depends on how crazy you want to go with maintenance. For $50 in additional fluids, I figured I had nothing to lose.