A petitioner may amend a petition at any time prior to the beginning of the meeting held by the commission pursuant to Section 2074.2. However, if the commission determines that the amendment is substantive, the commission shall resubmit the petition to the department for review pursuant to Section 2073.5, publish notice of the amendment pursuant to Section 2073.3, and renotice or continue any hearing scheduled pursuant to Section 2074 in order to provide adequate opportunity for public comment.