1. 
Prior to the adoption of the Official Map or part thereof, or any amendments to the Official Map, the Board of Commissioners shall refer the proposed Official Map or part thereof, or amendment thereto, with an accompanying ordinance describing the proposed map, to the Planning Commission for review. The Planning Commission shall report its recommendations on said proposed Official Map and accompanying ordinance, part thereof or amendment thereto, within 45 days unless an extension of time shall be agreed to by the Board of Commissioners. If, however, the Planning Commission fails to act within 45 days, the Board of Commissioners may proceed without its recommendations.
2. 
The County and adjacent municipalities may offer comments and recommendations during said forty-five-day period in accordance with § 408 of the Pennsylvania Municipalities Planning Code. Local authorities, park boards, environmental boards and similar public bodies may also offer comments and recommendations to the Board of Commissioners or Planning Commission if required by same during said forty-five-day review period. Before voting on the enactment of the proposed ordinance and Official map, or part thereof or amendment thereto, the Board of Commissioners shall hold a public hearing pursuant to public notice.
After adoption of the Official Map, or part thereof, all streets, watercourses and public grounds on final, recorded subdivision and land development plans which have been duly approved by the Board of Commissioners shall be deemed amendments to the Official Map. Notwithstanding any other terms of this chapter, no public hearing need be held, or notice given if the amendment of the Official Map is the result of the addition of a plan which has been duly approved by the Board of Commissioners.