Cal. Corp. Code § 13335

Any association may, upon resolution adopted by its board of directors, enter into all necessary and proper contracts and agreements and make all necessary and proper stipulations, agreements and contracts and arrangements with any other cooperative or other corporation, association, or associations, formed in this or in any other State, for the cooperative and more economical carrying on of its business or any part or parts thereof. Any two or more associations may, by agreement between them, unite in employing and using or may separately employ and use the same personnel, methods, means, and agencies for carrying on and conducting their respective business.