Wis. Stat. § 767.803

If the father and mother of a nonmarital child enter into a lawful marriage or a marriage which appears and they believe is lawful, except where the parental rights of the mother were terminated before either of these circumstances, the child becomes a marital child, is entitled to a change in birth record under s. 69.15 (3) (b), and shall enjoy all of the rights and privileges of a marital child as if he or she had been born during the marriage of the parents. This section applies to all cases before, on, or after its effective date, but no estate already vested shall be divested by this section and ss. 765.05 to 765.24 and 852.05. The children of all marriages declared void under the law are nevertheless marital children.