All benefits under any blanket disability policy shall be payable to the person insured, or to his designated beneficiary or beneficiaries, or to his estate; except, that if the person insured be a minor or mental incompetent, such benefits may be made payable to his parent, guardian, or other person actually supporting him; or if the entire cost of the insurance has been borne by the employer such benefits may be made payable to the employer. Provided, however, that the policy may provide that all or any portion of any indemnities provided by such policy on account of hospital, nursing, medical or surgical services may, at the insurer’s option, be paid directly to the hospital or person rendering such services; but the policy may not require that the service be rendered by a particular hospital or person. Payment so made shall discharge the insurer’s obligation with respect to the amount of insurance so paid.