Mo. Rev. Stat. § 470.090

All persons, bodies politic and corporate, named in such information as terre-tenants or claimants to the estate, may appear and plead to such proceeding, and may traverse or deny the facts stated in the information and the title of the state to the lands and tenements therein mentioned and described, at any time on or before the third day after the return of such scire facias; and any other person claiming an interest in such estate may appear and be made a defendant, and plead by motion for that purpose, in open court, within the time allowed for pleading.