§ 189-b. Changing number of trustees. Any incorporated church or society to which this article is applicable may, at an annual corporate meeting, change the number of its trustees to any number from three to twelve and classify them so that the terms of one-third as nearly as possible expire each year, provided that notice of such intended change be included in the notice of such annual corporate meeting. No such change shall affect the terms of the trustees then in office, and if the change reduces the number of trustees, election shall not be held to fill the vacancies caused by the expiration of the terms of trustees, until the number of trustees equals the number to which the trustees were reduced. Whenever the number of trustees in office is less than the number so determined on, sufficient additional trustees shall be elected to make the number of trustees for the ensuing year equal to the number so determined on. The trustees so elected up to and including as nearly as possible one-third of the number so determined on, shall be elected for three years, the remainder up to and including as nearly as possible one-third of the number so determined on for two years and the remainder for one year.