Wis. Stat. § 767.815: Enlargement of time in a paternity proceeding.

The time for service of summons and petition under s. 801.02 (1) in a paternity proceeding may be extended as provided in either sub. (1) or (2):

(1) Good cause. Upon the petitioner’s demonstration of good cause, the court may without notice order one additional 60-day extension for service of the summons and petition.

(2) Reasonable grounds; due diligence. The time for service may be extended until the date the summons and petition are actually served, if both of the following apply:

(a) There are reasonable grounds to believe that before the time for service under s. 801.02 (1) or sub. (1) expired the respondent knew that the mother was pregnant and that the respondent may be the father.

(b) Due diligence was exercised in attempting to serve the respondent, before he was actually served.