[torchia]

If your car is pre-lci then you won't have can3 on zgw. if i am not wrong the can3 comes only on ZGW2

When BMW build the car they assign different part number to FRM which will not show up on ETK. when i look on eBay to buy some i need to ask seller for a vin from which particular FRM was taken from to see if car had LED or Xenon headlights. However there are some people on this forum who know how to find out what FRM capable off by HW version on it. 
But when you buying a brand new from BMW they have only one part number, and that FRM will cover all the options - full  version.

The CAN3 connects to the ZGW , ZGW is your ROUTER on the car which controls all the signals. The FRM does not have CAN3 connection, CAN3 on ZGW gets converted in to CAN2 and sent to FRM and vice versa.

Ahhh okay that makes WAY more sense. So I need to see if my ZGW has CAN3, and if it doesn't I need to get one that does.

Looks like my ZGW should be part 61359360344 or 61359380333 to work? (link - it's hard to tell which one should be right).

And here is the FRM page, you're saying that none of them will work except 61356992947?

Also thanks for the rest of the notes about the pins and supply lines, that's super helpful.