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, contracts, and arrangements with any other corporations or associations, formed in this or any other State, for the co-operative or more economical carrying on of its business, or any part 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 businesses.