Have you ever been annoyed by people who do not seem to understand the concept of personal space? Maybe some relative with zombie halitosis? In international politics, this type of thing is common. Big countries like to stand much too close to small countries and, preferably, boss them around. If you think Aunt Josie is bad, you have not had a hug from Tsarist Russia... This brings us to a new concept in "Heir"; Spheres of Influence. At the cost of some prestige, powerful nations can extend their Sphere of Influence over weaker nations by means of a new diplomatic action. This is similar to a guarantee of independence, but any form of meddling (offers of alliance, guarantees, military access, etc) by an outside power will yield a Casus Belli. A sphere of influence can normally only be reduced by force (peace option) or if the balance of power shifts enough. The system provides a new use for prestige and a reason for the great powers to go to war with each other.
That's it for now. Further morsels next week, amigos!