Except in cases of emergency, having determined the necessity for the service of a senior judge, the requesting judge shall certify the reason such service is required, which shall include an order of appointment giving the scope and tenure of such requested service as in the discretion of the requesting judge is necessary to meet the need. Such certificate and order shall be filed in the office of clerk of superior court of the court in which service is to be performed and with the district administrative judge of such district.