38 CFR § 3.52 - Marriages deemed valid.
Where an attempted marriage of a claimant to the veteran was invalid by reason of a legal impediment, the marriage will nevertheless be deemed valid if:
(a) The marriage occurred 1 year or more before the veteran died or existed for any period of time if a child was born of the purported marriage or was born to them before such marriage (see § 3.54(d)), and
(b) The claimant entered into the marriage without knowledge of the impediment, and
(c) The claimant cohabited with the veteran continuously from the date of marriage to the date of his or her death as outlined in § 3.53, and
(d) No claim has been filed by a legal surviving spouse who has been found entitled to gratuitous death benefits other than accrued monthly benefits covering a period prior to the veteran's death.
Definition, marriage. See § 3.205(c).