38 C.F.R. § 10.29
A dependent, in subsequent position in the order of preference as defined in section 601 of title VI of the Act, as amended, who makes claim for the benefits of the Act in consequence of the death of a dependent who made application and who stood in preferential position as defined in section 601 of the act, as amended, shall be required to furnish, in support of such claim, proof of death of said dependent. Proof of death of said dependent shall be in accordance with the requirements for proof of death as outlined in the regulations of Department of Veterans Affairs. A dependent who makes claim for the benefits of the act because of remarriage of a widow who did not make and file application before remarriage shall be required to furnish in support of such claim proof of remarriage of said widow. Proof of remarriage of said widow shall be in accordance with the requirements for proof of marriage as outlined in regulations of the Department of Veterans Affairs.
38 C.F.R. § 10.29