(1) [A vacancy in the service may be temporarily filled] by the Appointing Authority by appointing thereto in an officiating capacity an officer whose name is included in the list prepared under Rule 21 or in the lists under Rule 25 :
Provided that till the preparation of the first list or in case the list is exhausted, a vacant post may be filled by the Appointing Authority by appointing thereto a [person] eligible for appointment to the post by promotion or by appointing thereto temporarily a person eligible for appointment by direct recruitment to the service under the provision of these Rules :
Provided further that if all the officers in the grade or category from which appointment by promotion can be made under these rules, have already been promoted and no Officer is available from that grade of category the appointing authority may fill such vacancy by promotion from the grade or category next below such grade.
(2) No appointment made under sub-rule (1) shall be continued beyond a period of [one year] without referring it to the Commission for their concurrence and shall be terminated immediately on their refusal to concur.