Vt. Stat. Ann. tit. 15, § 513

A complaint to annul a civil marriage on the ground that one of the parties was under the age of 16 years may be brought by the parent or guardian entitled to the custody of such minor or by a person admitted by the court to prosecute the same as the next friend of such minor. However, such marriage shall not be annulled on the complaint of a party of legal age at the time it was contracted nor when the parties, after they attained the age of consent, freely cohabited as husband and wife.