I want to add 3 new sets of Tactical HUD's for three new forces.
Can anyone assist please.

I know, for Generals and Generals Zero Hour, WND files make the changes for them.
However, when I looked for all WND Files in CNC3TW, I got nothing.

The Mod SDK's documentation briefly mentions UI editing, saying that it's only possible to do retextures of existing UI elements. It may be outdated, as I've seen mods that move UI elements around.

One thing I can remember is that I think jonwil made a tool to convert the UI files into XML so you can edit them. You should try searching for that.

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Isn't Bibbers asset extractor also able to do that?
https://bibber.eu/downloads/cnc-red-alert-3/ 

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That is not what that tool is used for, LOL.

I'm not sure if the asset extractor can handle the UI files. But I know it works for C&C 3 just as well as RA3.

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I intend to add three new forces to my MOD,
I have made the custom UI-HUD's for them, but I do not know how to include them so the new forces use them.

Perhaps downloading, unpacking and analising files from "The Forgotten" mod (which adds 1 new faction, without deleting GDI nor Nod nor Scrin) will give you an answer.