Wis. Stat. § 48.871
In the case of a recommendation by a guardian, the guardian shall file with its recommendation satisfactory evidence of its authority to file such recommendation relative to the adoption of the minor. In the case where the parents' rights have been judicially terminated, this evidence shall be a certified copy of the order terminating their rights and appointing the guardian. In other cases of a guardian appointed by a court, this evidence shall be a certified copy of the order appointing it guardian. In the case of a guardian having the authority to consent or file its recommendation under an instrument other than a court order, valid under the laws of another state, that instrument shall serve as evidence of the authority to consent or file its recommendation.
Wis. Stat. § 48.871