Hello Bryan,
yes, thanks for your explanation!

I've also already experimented with this method long time ago (when I tried to allow entering moves with the PC keyboard instead of the mouse),
but the problem is, that you always have to press 2 keys at the same time on the keyboard (e.g. A and 2 for a mouseclick on a2),
and that's not really comfortable. But for your external board this is indeed a very clever method.

Since your way to find out the correct square for these 'Unnamed Key' entries in the Tab menu is very time-consuming, I've now added the right square names to the board sensors in ALL devices, i.e. now you see "Square A1", "Square A2" etc. instead of 'Unnamed Key' in the Tab menu. Of course you still have to make these assigment manually, but at least you see now the board square in the list and can immediately enter the right keys.
So it will be much easier for you to add more CB-Emu modules to your external board.

Here is this new Update3:
https://www89.zippyshare.com/v/V8LRJfR4/file.html
(apart from these new square labels nothing has changed, so you can just use these new EXEs without having to change anything in your existing configuration).

Now I have one more question:
With your method moves made on your external board are sent to CB-Emu on the PC, but the other direction is not possible, right?
IOW, when the chess module in CB-Emu makes a move, you still have to look at the PC screen to see this move, i.e. the board LEDs on your external board do NOT show this move, right?
Or have you even found any additional trick, so that your external board 'gets' the moves from CB-Emu?

In principle this should be possible, especially now with the new PGN feature in the last versions, because whenever CB-Emu writes a move into 'gamelog.pgn', it could also send this move to any other target (file, console, screen, USB etc.).
So in fact a 'full' communication (only for moves of course) between an external board and CB-Emu should be possible -
only the direction 'CB-Emu to external board' would have to be solved.

Regards,
Franz