This is a question I've had for a while, will the French get colonial troops class?
I mean, North Africans and Saharan Africans, Madagascans and Vietnamese fought for France, and they had different uniforms then French born troops, different designations also. Tirraleurs, Zouaves, , Goumiers (Though Goumiers didn't fight outside of Africa in WWI, so their addition wouldn't make sense), service in the FFL, and finally the Tonkiese Riflemen (They fought only in Asia, however, so they're in the same situation as the Gourmiers).
I thought it'd be a good idea too add some of colonial units for France, one FFL class (Under specialists?), along with the Senegalese Tirraleurs and the Algerian Zouaves. Germany didn't use their colonial citizens in the War to the same extent of the Brits and French, but I'm guessing there were some East Africans under the Kaiser (Not sure though, I've spent most of my time researching France in WWI, and to a lesser extent Britain).
For the Brits, I'd have the Gurkhas. They fought on the Western front, lost a lot of men there also. Of course I'm just shooting the breeze here, just some ideas I'm putting forward.