Well you've answered the gist of my question, but I'm still confused about this coven's retention of power. For instance, you mentioned that within the coven itself, they will have a hierarchical caste system which may range from servants to the Lords, but who brings home the bacon? Typically, in relation to our own world, civilization emerged from a development of agriculture and an abundance of food, in which political systems only emerged because there was now a surplus of resources to retain an army. Political factions always rely on force or some industry in order to maintain their dominance. So do the D'Cerf's utilize force or industry? Do they use fear and racketeering to engender continual financial/resource support from the, let's say, outlying regular serf villages whom they impose taxes on (taxes in the form of actual currency, or just a percentage of supplies)? Or do they maintain power and patronage with their mysterious underlying occult, which may also put the serfdom in a perpetual state of zealous traditional support? Do they convince the public that the other covens are the enemy?
Essentially the question can be boiled down to; how do they garner support to fill the storehouse, and what methods do they use to galvanize public opinion to prop up their reign?
I ask these questions to clarify because this is the aspect that really drew me in.