If entire FC buys a house its their own decision on how they play their own accounts, each one member of certain FC is an individual player just like you, paying sub like everyone else and is not restricted to anything. Maybe they have just planned it all to have all their houses in the same ward, idk whats a problem with it?
If someone is not using their house then there is already a solution and i wrote it in my previous comment that SE could simply just implement a monthly tax and thats basically it.
We dont need instanced housing, if someone wants to buy a house he will sooner or later.