may provide for the local education authority to have power to determine, in relation to every election of parent or teacher governors, the school or schools within the group the parents of registered pupils at which, or (as the case may be) the teachers at which, are to be entitled to stand and vote at the election; and

shall, where it does so, provide for it to be the duty of the authority to ensure that the position after any such election will be that there is no school within the group which will not have had an opportunity to have so participated in the election of at least one of the parent or (as the case may be) teacher governors of the group.