Upon receipt by the boards of commissioners of the districts proposed for consolidation, hereinafter referred to as the "consolidating districts", of the lead county auditor's certificate of sufficiency of the petitions, or upon adoption by the boards of commissioners of the consolidating districts of their resolutions for consolidation, the boards of commissioners of the consolidating districts shall, within ninety days, enter into an agreement providing for consolidation. The agreement shall set forth the method and manner of consolidation, a comprehensive plan or scheme of water supply, sewer, and drainage services for the consolidated district, and if the comprehensive plan or scheme of water supply, sewer, and drainage services provides that one or more of the consolidating districts or the proposed consolidated district issue revenue bonds for either the construction or other costs of any part or all of the comprehensive plan, or both, then the details thereof shall be set forth. The requirement that a comprehensive plan or scheme of water supply, sewer, and drainage services for the consolidated district be set forth in the agreement for consolidation shall be satisfied if the existing comprehensive plans or schemes of the consolidating districts are incorporated therein by reference and any changes or additions thereto are set forth in detail.