Hi tutkarz, that depends a lot on what you are aiming for. Is it something like in Civilization, where one unit of troops still pretty much functions like a unit in my toolkit only that it has multiple skeletal meshes, then no, that is quite easy. If you want something else, where two different units can move onto the same tile and you want to be able to selectively select one of these units while they are on the same tile, you would need to rework several core systems.