Alas, Dom 2 prioritises which mod takes precedence over which: if memory serves, the last mod (alphabetically) rules over all previous mods, so two mods cannot change the same thing. I guess the same will happen if you copy-paste all .dm into one monster .dm file: the one last change should be the one ruling them all.
You could have some fun with the special nations however: if you add SC Units mod and a mod changing all the nations, you will have units taking random values, and assorted fun.
