After adoption of the official map, or part thereof, all streets, watercourses and public grounds and the elements listed in section 401 on final, recorded plats which have been approved as provided by this act shall be deemed amendments to the official map. Notwithstanding any of the other terms of this article, no public hearing need be held or notice given if the amendment of the official map is the result of the addition of a plat which has been approved as provided by this act.
53 P.S. § 10403