It should come as no surprise, but the folks operating under the label "Brookhaven Yes!" will indeed be running the new city. As reported in the AJC they have established many a Task Force to assess various aspects of how the City will be run. But before you ask, the answer is: No, you cannot have access to any documents or meetings until and unless they bloody well feel like it.
You see, all that transparency stuff like open records requests and open meetings only applies to government operations, and Brookhaven Yes! isn't a government. Yet.
There are a few rays of hope. First, by not opening these meetings to the public and following the requirements that will soon be applied to the real city the members of this group who are running for political office may take a serious hit. Mistrust seems a significant factor in politics these days.
And the Governor, though he has yet to act and may be stalling, will appoint a commission to coordinate the efforts of city formation. At that point there will be a legitimate government entity involved and to the extent that entity does anything it will be subject to open meeting and records law. Or it will be subject to legal action.
To date these advocacy non-profits have been hiding behind their corporate shields. That is about to change.