Wis. Stat. § 879.15: Appearances, how made.

In any proceeding in the court, appearances shall be made as follows:

(1) A minor or individual adjudicated incompetent shall appear by a guardian ad litem or by the guardian of his or her estate, who may appear by attorney, or by another person under the doctrine of virtual representation as provided in s. 879.23 (5);

(2) A personal representative shall appear by attorney; and

(3) Every other person shall appear in person, by attorney or, if in the military service, by an attorney-in-fact.