Section 7. Proposed changes in the boundary lines between adjoining towns shall be submitted to each of the towns affected by the change for their concurrence at town meetings. If approved, they shall be submitted to the department of highways of the commonwealth for review as to clarity and engineering accuracy. Said department may recommend wording to accurately describe the proposed change, but may not alter the intent. The description as approved by said department, shall then be submitted to the next regular session of the general court. If ratified and accepted by the general court, the person, corporation, town, county, or state department initiating the change, shall, at his or its own expense, engage the services of a registered land surveyor to locate and define such change and determine the position of each angle and corner in such new boundary line. A plan of the change and any computations pertaining to it shall be submitted to said department of highways for approval as to accuracy. The selectmen of the contiguous towns, shall, within six months after passage of the legislation, place such monuments at the new points determined, and place such marks on them, in addition to initials, as the department may prescribe and in the manner required by section four. Monuments marking angles and corners in town boundaries, the position of which has not been changed, shall be re-marked in the manner indicated by said department so as to establish a uniform system of designating angles and corners of town boundary lines.