Section 3 of chapter 161B of the General Laws, as appearing in the 2012 Official Edition, is hereby amended by striking out the third paragraph and inserting in place thereof the following 2 paragraphs:-

Any city or town, or group or combination of cities or towns, other than a city or town included in the Massachusetts Bay Transportation Authority in which the Authority operates fixed route bus service may, with the approval of a city manager in the case of a city under a Plan E form of government, the mayor and city council in the case of all other cities, or the board of selectmen in the case of a town and subject to the approval of the advisory board to a regional transit authority, join an authority which is not separated from the city or town or group or combination of cities and towns by more than 1 other municipality.

Notwithstanding any general or special law to the contrary, a city or town that is a member of an authority may, with the approval of the city manager in the case of a city under a Plan E form of government, the mayor and city council in the case of all other cities, or the board of selectmen in the case of a town, join an additional authority, subject to the approval of the advisory board of the additional authority and provided that the city or town adjoins a city or town that is a member of the additional authority.