I think you'll know who the players are from the beginning anyway, because the group would have to come together and file a complaint, and in the complaint that would be filed with the agency, clearly, the members of that group would be enumerated in the complaint. Also, the nature of the complaint and how it applied to all members of that group would have to be spelled out in some considerable detail.
As I say, we would see a formal registration process as an unnecessary bureaucratic approach to something where there's already an administrative approach in place that can deal with this quite satisfactorily.