Vacancies in the board of trustees, occasioned by removals, resignations or otherwise, shall be reported to the proper official and be filled in like manner as original appointments, except that if the vacancy is an unexpired term, the appointment shall be made for only the unexpired portion of that term. No member of the board shall serve for more than three successive full terms and shall not be eligible for further appointment to the board until two years after the expiration of the third term. No trustee shall receive compensation as such, and no person shall be employed by the board who is related either by blood or by marriage to any trustee of the board.