(1) The addition of other parties to an arbitration would jeopardize the commission's ability to complete the arbitration within the limited time frame imposed by the 1996 Act and ARM 38.5.4020 by lengthening the proceeding and detracting from the arbitrator's ability to move forward expeditiously on the merits of the petition for arbitration. Intervention shall be limited to the Montana consumer counsel, the sole statutory intervenor, who shall have the rights and duties as directed under Montana law. The Montana consumer counsel, if he requests intervention, shall intervene as early as practicable and no later than 25 days after the petitioner files a request for arbitration.