The administrator shall be a party in interest in any proceeding for the appointment or removal of a guardian or for the removal of the disability of minority or mental incapacity of award, and in any suit or other proceeding affecting in any manner the administration by the guardian of the estate of any present or former ward whose estate includes assets derived in whole or in part from benefits paid by the veterans’ administration before or after September 17, 1947. Not less than five days prior to hearing in such matter, notice in writing of the time and place thereof shall be given by mail, unless waived in writing, to the office of the veterans’ administration having jurisdiction over the area in which any such suit or proceeding is pending.