The Group C representatives would also be concerned with the world outside the C group, being the caretakers of the cumulative interests of Group C, and working on optimizing Group C's role within an even bigger playing field. This can go all the way up to a coordinating council for the whole planet. The scope of planetary council members' business would be the optimum interaction between the major geographical and cultural regions on the planet. It would also be their business to represent the whole planet in any interactions with representatives of other planets. Notice that integral to this scheme is the principle that power flows from the ground up.
Power flows from individuals to communities to societies to civilizations.
It doesn't go the other way. It is not the business of governments to grant rights or privileges to individuals or communities. The people grant limited privileges to their representatives, bestowing them the job of representing them well. The privileges of representatives can be revoked at any time by those bestowing that power. Global or regional leaders will not command armies.