CA Gov't Code Section 66456.1

Multiple final maps relating to an approved or conditionally approved tentative map may be filed prior to the expiration of the tentative map if: (a) the subdivider, at the time the tentative map is filed, informs the advisory agency of the local agency of the subdivider’s intention to file multiple final maps on such tentative map, or (b) after filing of the tentative map, the local agency and the subdivider concur in the filing of multiple final maps. In providing such notice, the subdivider shall not be required to define the number or configuration of the proposed multiple final maps. The filing of a final map on a portion of an approved or conditionally approved tentative map shall not invalidate any part of such tentative map. The right of the subdivider to file multiple final maps shall not limit the authority of the local agency to impose reasonable conditions relating to the filing of multiple final maps.