(a) If a regional planning commission prepares and adopts a regional plan, the regional plan or a portion thereof may then be adopted by the legislative body of any member municipality as its plan in accordance with subchapter 5 of this chapter.

(b) The legislative body of any municipality may designate the regional planning commission of a region of which such municipality is a member as the planning commission of such municipality, and, if so designated, the regional planning commission shall thereafter act as the planning commission of such municipality until a planning commission is created under section 4321 of this title or until such regional planning commission notifies such legislative body, in writing, that it no longer will so act. (Added 1967, No. 334 (Adj. Sess.), § 1, eff. March 23, 1968.)