Wis. Stat. § 877.03: Multiple personal representatives to be considered one.

In an action or proceeding against more than one personal representative of an estate, all of the personal representatives shall all be considered to be representing the decedent. Service of the summons on one personal representative shall constitute service on all, although the plaintiff may serve each of them. Judgment shall be rendered as if all had been served and execution may be issued against the property of the decedent as if all had appeared.