Whenever a person is employed by two or more districts under the jurisdiction of a single county superintendent of schools, the governing boards of the districts may authorize, in writing, the county superintendent of schools to act as their agent in the payment of the salaries due such person from the districts. If such authorization is given, the county superintendent of schools may draw a warrant on the county school service fund in payment of the total salaries due such person and shall immediately draw requisitions in favor of the county school service fund against the proper funds of each district for the amount paid by him to such person on account of such district.