(1) An impact plan or a proposed amendment to an approved plan may be modified during the review period, the negotiation period, or an extension of either, by mutual consent of the developer and the local government units affected by the modification. Modifications must meet the following requirements:

(a) Modifications must be submitted in writing to the board and to all local government units that are party to the plan.

(b) The copy filed with the board must bear the signatures of the authorized representatives of the developer and of the governing body of each local government unit that is a party to the modification.

(c) If there is a need to modify the format of the plan and if the modification does not affect the substantive provisions of the plan, the governing body of the county may act on behalf of all local government units within the county when it concurs with the modification of format.

(d) Any modification submitted less than 30 days prior to the end of the review period must carry with it a request from the local governing body for an extension which allows 30-day review of the modification.

(e) All modifications must be incorporated into the plan before the board will approve it. The modified plan must comply with the form and content requirements for an impact plan as provided by parts 3 and 4 of Title 90, chapter 6 of the Montana Code Annotated and by the administrative rules adopted by the board. In the modified plan the table of contents, summary, schedule of payment, and, if a part of the plan, the developer's written guarantee, must accurately contain and reflect the modifications. Obsolete material must be deleted from the plan through the use of replacement pages that contain and reflect the modifications or, if the use of replacement pages is not feasible, obsolete material must be deleted by specific reference.

(f) The board may allow revisions to format following the review or negotiation period, or an extension of either, to the extent that such revisions are necessary to incorporate the modifications into the plan in order to comply with ARM 8.104.203.