Cal. Educ. Code § 35110

When the membership of the governing boards of an elementary school district and a high school district is the same, and if the certificated employees in both districts have selected the same employee organization to be their exclusive representative for purposes of Chapter 10.7 (commencing with Section 3540) of Division 4 of Title 1 of the Government Code, the board may adopt a resolution making the provisions of this article applicable to each district under its jurisdiction.