Brokeback - You are welcome.
The power structure of the WTS is determined by their Charter. They are legally bound to follow their Charter.
I have only ever been able to find a copy of the 1945 WTBTS Charter and I don't know what, if any, amendments have been made to the charter since that time. I have never found any other documents pertaining to their charter.
http://sj.rozcesti.org/system/files/1945_Charter_of_WTBTS.pdf
It is in the charter that one discovers that "the Society" is made up of a select group of men (300-500) and the charter also lays down the requirements for membership in that select group and how the lines of power are to be arranged.
I have never found a membership list for "The Society". Apparently, that list is as secret as their pedophile list. If anybody has a list of the men who hold Society membership, I would be interested in accessing it.