When a joint district retirement plan is established there shall be created in the treasury of the county in which the districts are located, or, if the districts are located in more than one county, in the treasury of the county selected by the governing boards of the districts meeting in joint session, and open upon the books of the auditor and treasurer of the county, a trust fund account designated as the “joint district retirement fund.” All moneys, whether from contributions by teachers or other employees, or by the districts, or from any source, properly belonging to the joint district retirement fund shall be placed in the fund. Upon approval of the joint district retirement board all incidental expenses, including actual and necessary clerical or other help, incurred in carrying out the provisions of this chapter shall be paid out of the fund and in the same manner as other expenditures are paid from district funds.