Hi guys. I want to be able to make some units like the marine, which is cheaper than mech. infantry, not become obsolete once I develop mech. infantry. I can't seem to find info on this in the wiki. Do I basically just have to erase the part in the xml file that says it can upgrade to mech. infantry? That would suck because I still want to be able to upgrade current marines at the same time still be able to build new ones.