I have an idea for a mod with a lot of technology steps. Currently 10 are planned. if you start you can only train the normal pikeman but if you rech tech lvl 2 I want that the pikeman disappears in the barracks and you can then train the Russian spearman which is slightly better then the pikeman. Once you reach tech lvl 3 he also disappears and becomes replaced with pikeman Portugal which is again slightly stronger. Disadvantage of this mod would be of course that no different nations are available since more or less all units are available for every nation. Any idea how I could solve that? How can I replace a unit.