Mo. Rev. Stat. § 475.065

When application is made for the appointment of a guardian or conservator for two or more minors or incapacitated or disabled persons who are children of a common parent, or are parent and child, or are husband and wife, it is not necessary that a separate petition, bond or other paper be filed for each minor or incapacitated or disabled person and the guardianship or conservatorship of all may be considered as one proceeding except that there shall be a separate accounting when the guardianship or conservatorship terminates as to one ward or disabled person but not as to the others.