Mon Jan 18, 2016 6:34 pm
Principally you can give orders to any nation. The game will not prevent you from doing that--of course if you're playing the UK and giving orders to the French that's not exactly kosher, but it's your game.
If you just want to get, for example, Prussia to move that one stack to right where you want it, if you load Prussia and plot and save the movement orders for that one stack, that's all that Prussia will do that turn, other than further orders you have have issued. Once the game engine finds an orders file for that factions it will not attempt to give that faction further orders that turn. Once you've given orders to a faction, the first turn if the game engine doesn't find orders save by you, it will ask you if you want the AI to takeover that faction. Tell it yes and it will resume controlling that faction.
If you just want to tell a coalition partner or another ally where you want it to attack or concentrate its forces, open the Interest Painter with <Tab>, select the flag of the faction you want to influence and paint the regions accordingly. Then the AI will use the influence you've painted to plot that faction's moves. That's probably what you want to do.
