Wis. Stat. § 786.26: Future estates may be sold.

Any real estate or interest therein which may at any time in the future be owned or possessed by any after-born child or by any person, whether in being or not, known or unknown, who shall or may become interested therein under and by virtue of any deed or other instrument, or by any last will and testament, may be sold, mortgaged, leased or otherwise disposed of as provided in ss. 786.26 to 786.35.