I was thinking it would be interesting to have a feature where you could buy other idol production companies and absorb them into your group. Maybe have policies set where the idols you get from "buying out" the company either become a sister group or they are managed autonomously and you get a cut of the revenue instead of all of it by taking direct control of the group.
Also, it would be nice if you could set policies for all groups or have different policies for differ sister groups.