Ed. Code, § 45120

If all or any part of any district or districts which is unified with all or any part of a district, has, or have, the merit system prior to the date of the reorganization election, all employees not legally requiring certification qualifications of the reorganized district shall be employed in accordance with Article 6 (commencing with Section 45240) of this chapter if a simple majority of the classified employees of the reorganized district voting on the adoption of a merit system approve its adoption pursuant to Section 45221. If no such election is requested by the classified employees of the reorganized district pursuant to Section 45221, adoption of a merit system shall be effective only if the number of classified employees from the merit system district who are to become employees of the acquiring district equals or exceeds the number of classified employees of the acquiring nonmerit system district. If on the date of such reorganization election, two or more of the said defined districts of such reorganized district have merit systems, the reorganized district shall adopt a single merit system which shall contain all provisions necessary to secure to all employees the rights guaranteed by Section 45121 of this code.

Seniority of the personnel of the reorganized district shall be established as of the date of original employment in the district or districts as defined above. Where there are more than a sufficient number of employees for a given classification under the provisions of Article 6 (commencing with Section 45240) of this chapter, such personnel shall be retained in employment for a period of not less than two years as if the reorganization had not occurred but without prejudice to the powers of the personnel commission and the governing board of the new unified district to reasonably reassign such person. If at the expiration of such period, upon a finding made by the personnel commission that there are excess personnel in any given classification, such personnel shall, if the governing board so directs, be placed upon appropriate reemployment lists for 39 months, and shall, if so placed, be offered and may accept positions of lower rank in their line of promotion in the order of seniority as established by this section in accordance with rules drawn in compliance with the provisions of Article 6 (commencing with Section 45240) of this chapter. The acceptance of a position in lower rank in accordance herewith shall not be deemed to constitute a waiver of the right to reemployment at the original level should a vacancy at such level occur within the period mentioned in this section.