Section 192. All provisions of law relative to the filing of policy forms with, and the approval of such forms by, the commissioner shall also apply to all forms of riders, endorsements and applications designed to be attached to such policy forms and when so attached to constitute a part of the contract; provided, that riders or endorsements used at the request of individual policyholders in connection with policies of life or endowment insurance relative to the distribution of benefits payable under their policies or to the reservation of rights or benefits thereunder, and riders or endorsements used under the ninth clause of section ninety-nine in connection with policies of fire insurance issued under section one hundred and two A, may be used, so far as consistent with law, without such approval. All such provisions of law shall also apply to all forms of riders or endorsements, designed to be attached to motor vehicle liability policies as defined in section thirty-four A of chapter ninety, providing for additional coverage permitted by section one hundred and eleven C.