Section 3A. Any number of cities or towns may, with the approval of their respective municipal officers and of the department, create or disband by a contract subject to the approval of the department a regional housing authority, with all of the powers and obligations of the constituent authorities, to act in the place of the several housing authorities, if any, theretofore existing. Such contract shall set forth the rights, powers and obligations of the regional housing authority within the several cities or towns in which it is to operate. Any unresolved dispute which may arise as to the rights, powers or obligations conferred by such contract shall be referred to the department for resolution.