The mixed-blood members of the tribe, including those residing on and off the reservation, shall have the right to organize for their common welfare, and may adopt an appropriate constitution and bylaws which shall become effective when ratified by a majority vote of the adult mixed-blood members of the tribe at a special election authorized and called by the Secretary under such rules and regulations as he may prescribe. Such constitution may provide for the selection of authorized representatives who shall have power to take any action that is required by this subchapter to be taken by the mixed-blood members as a group: Provided, That nothing herein contained shall be construed as requiring said mixed-blood Indians to so organize if such organization is by them deemed unnecessary. In the event no such approved organization is effected, any action taken by the adult mixed-blood members, by majority vote, whether in public meeting or by referendum, but in either event, after such notice as may be prescribed by the Secretary, shall be binding upon said mixed-blood members of the tribe for the purposes of this subchapter.