Conn. Gen. Stat. § 8-139: Joint action by two or more municipalities.

By concurrent action the legislative bodies of two or more municipalities: (a) May create a regional or metropolitan planning agency and may authorize such agency or the planning agency of any of such municipalities to make a comprehensive or general plan of the area included within such municipalities as described in section 8-127, and (b) may exercise the powers granted in this chapter to the legislative body of any municipality. In all matters under this chapter requiring the approval of the legislative body, such approval shall be by the legislative body of each municipality only as to the portions of the redevelopment plan situated in such municipality.