Whenever any employee whose injury or death is compensable under this chapter shall at the time of the injury be in the joint service of two or more employers subject to this chapter, such employers shall contribute to the payment of such compensation in proportion to their wage liability to such employee; provided, however, that nothing in this Code section shall prevent any reasonable arrangement between such employers for a different distribution as between themselves of the ultimate burden of compensation.
OCGA § 34-9-224