Given the 'it's just a thing you do' attitude Equestrians have for overriding somon'es free will to force them to comply with their own ethics and morals (see the Elements of Harmony...) I always assumed that Equestria diplomacy is simply: "Do as I say." "Or what." "Or you will do as I say and be happy about it." "Bullshit." *zap* "Now about that trade deal..." "Oh sure, anything you like!"