A Question on adding units

I'm working on a personal mod of the 16th/17th centuries, which of course requires that many factions are able to build pikes/muskets. My question is this:

Pike militia units seem to be a generic unit, in that they will take the faction colours of the faction they are recruited by in their model (unless of course there is a seperate pike militia unit for every faction that can train them). The same does not seem to be true of musketeers/professional pike units. If I were to add, for example, the French/Scottish pike unit to the English unit roster, would they still have the French/Scottish faction colours? Would the only way to 'fix' this be to edit the unit textures?