Final answer:
The owner is generally responsible for obtaining an amended Certificate of Occupancy, which is necessary when the possession date of a property changes.
Step-by-step explanation:
The responsibility to obtain an amended Certificate of Occupancy typically falls to the owner of the building. In the context provided, if the owner is unable to deliver possession on the agreed date, for reasons including but not limited to the loss or destruction of the residence or failure of prior residents to vacate, the agreement can be terminated by either party. In such a case, any sums paid under the agreement shall be refunded in full. However, if the terms of the agreement are not canceled by either party, the owner would likely need to obtain the amended Certificate of Occupancy to reflect the new date of actual possession before the residents can legally occupy the building.