Section 9D1/2. A county, except Worcester county, by vote of the county commissioners; a city having a Plan D or Plan E charter by majority vote of its city council, any other city by vote of its city council, approved by the mayor; a district, except as hereinafter provided, by vote of the registered voters of the district at a district meeting; a regional school district by vote of the regional district school committee; a veterans' services district by vote of the district board; a welfare district by vote of the district welfare committee; a district established under the provisions of section twenty-seven A of chapter one hundred and eleven by vote of the joint committee; may provide that it will pay in addition to fifty per cent of a stated monthly payment, as described in section nine D, a subsidiary or additional amount, with a correspondingly lesser amount to be paid by the surviving spouse of an insured or retired employee.

A town may provide for such payment by vote of the town or if a majority of the votes cast in answer to the following question which shall be printed on the official ballot to be used at an election in said town is in the affirmative:—''Shall the town, in addition to the payment of fifty per cent of premium costs payable by the surviving spouse of an employee or retired employee for group general or blanket hospital, surgical, medical and other health insurance pay an additional or subsidiary rate?'' Section nine D shall not apply in any governmental unit which accepts the provisions of this section.