There's currently a lot of talk about Physics.SE absorbing ThPhys.SE and Astro.SE. How is this carried out? Who decides, and where, on what policy is to be executed? Once it's decided, where, how and when is it carried out? Is there a top-down decision or is there a "suggestions box" of some sort?
I couldn't seem to find any similar mass-migrations that have happened before, so apologies if this information is sitting in an obvious place I missed...