ยง 1607. Powers  of  trustees when vacancies on board exist.  1.  While
  there is one vacancy in the office of trustee, the  two  trustees  shall
  have  all the powers and be subject to all the duties and liabilities of
  the three.   And while there are two  such  vacancies,  the  trustee  in
  office  shall  have  all the powers and be subject to all the duties and
  liabilities of the three, as though he were a sole trustee.
2. When a vacancy shall occur in the  office  of  trustee,  the  board
  shall  immediately  call  a special meeting of the district to fill such
  vacancy.
Structure New York Laws
Title 2 - School District Organization
Article 33 - Common School Districts
1601 - Trustees Constitute a Board and Body Corporate.
1602 - Number of Trustees; Determination of Change.
1603 - Property Held by Trustees as Corporation.
1604 - Powers and Duties of Trustees.
1604-A - Temporary Investment of School Moneys.
1605 - Powers and Duties of a Sole Trustee.
1606 - Mode of Exercise of Trustees' Powers.
1607 - Powers of Trustees When Vacancies on Board Exist.
1608 - Estimated Expenses for Ensuing Year.
1609 - Annual Report of Trustees of Certain Joint Districts.
1610 - Trustees' Annual Report to District.
1611 - Penalty for Failure of Trustee to Account.
1612 - Payment by Trustee to Successor.
1613 - Trustees' Right of Action Against Predecessor.
1614 - Notice of Non-Payment of Moneys Apportioned.
1615 - Taxation for Expenses Incurred by Trustees.
1616 - Issuing Order in Excess of Available Funds a Misdemeanor.