(1) The Presiding Officer shall notify all parties of their right to appeal the Decision and Order.(2)Appeal of Decisions to the Commissioner. Any person aggrieved by a Decision and Order approving or disapproving a Rate Filing or a Revised Rate Filing issued in a Proceeding conducted by a Presiding Officer designated by the Commissioner, which the Commissioner has not affirmed, may appeal the decision to the Commissioner pursuant to M.G.L. c. 26, § 7. Upon the docketing of an appeal under M.G.L. c. 26, § 7, the Commissioner shall set a date by which the aggrieved person must file a brief which states the grounds for the appeal and the relief requested. A person who fails to timely file a brief thereby waives its right to appeal. The Commissioner shall notify all parties of the appeal, and of the filing date for the appeal brief. If the Commissioner determines, upon review of the brief and the record, that the appeal is without substantial merit, he or she may issue a decision denying the appeal. Otherwise, the Commissioner shall set a filing date for briefs by parties to the Proceeding and shall issue a decision after that date. The Commissioner may modify, affirm or reverse the Presiding Officer's decision, in whole or in part.