11. Persons to fill the seats in the Federal Assembly allotted to any group of States mentioned in Division XVI of the Table of Seats as entitled to appoint persons to fill three such seats shall be appointed in the prescribed manner by the Rulers of such of the States in the group as have acceded to the Federation :
Provided that—
(a) until the Rulers of two of those States have so acceded, all the three seats shall remain unfilled; and
(b) until the Rulers of four of those States have so acceded, two of the three seats shall remain unfilled; and
(c) until the Rulers of six of those States have so acceded, one of the three seats shall remain unfilled.
Seats in the Federal Assembly remaining unfilled by reason of the provisions of this paragraph shall be treated as seats remaining unfilled for the purposes of the last preceding paragraph.