California Code, Education Code - EDC § 35544

Whenever territory is transferred or added by means of reorganization to another district in which trustee areas have been established, the territory being transferred shall become a part of the trustee areas to which it is contiguous.  In the event that the territory being transferred is contiguous to more than one trustee area, terms of agreement to the transfer may include provisions for the division of the transferred territory among the trustee areas to which it is contiguous.