Indiana Code Title 22. Labor and Safety § 22-3-3-31

Sec. 31. Whenever any employee for whose injury or death compensation is payable under IC 22-3-2 through IC 22-3-6 shall at the time of the injury be in the joint service of two (2) or more employers subject to IC 22-3-2 through IC 22-3-6, such employers shall contribute to the payment of such compensation in proportion to their wage liability to such employees;  provided, however, that nothing in this section shall prevent any reasonable arrangements between such employers for a different distribution as between themselves of the ultimate burden of compensation.