In our particular case, the governing documents stated a special shareholders meeting is needed to amend the Proprietary Lease or the Bylaws (not the House Rules). However, a shareholder could hand in a proxy if s/he preferred. Our coop attorney said we had to be very meticulous about the amendment process as most amendments that get tossed out by the courts are invalidated not because of the content but because they were adopted in violation of proper procedures.