When the owners of two or more lots in the C-3 District form a joint agreement to eliminate the side and rear yard parking setbacks, pursuant to the requirements of Schedule 1155.07, any parking areas located on such lots shall be considered one parking lot and shall comply with the landscaping requirements for the interior of parking lots as set forth in Section 1167.05. Maintenance and upkeep of such landscaped areas shall be agreed upon by the owners in the joint agreement required in Schedule 1155.07.