Mo. Rev. Stat. § 429.200
In case of the death of any of the parties specified in section 429.190, whether before or after suit brought, the personal representative of such deceased party shall be made plaintiff or defendant, as the case may require, and it shall not be necessary to make the heirs or devisees of such deceased persons parties to the suit; but if there is no personal representative of such deceased person, then his heirs or devisees may be made parties, and if any of the heirs or devisees are minors under the age of eighteen years, their guardians or conservators of their estates shall be made parties with them; but if such minors shall have no guardians or conservators of their estates, the court in which the suit is pending shall appoint guardians ad litem for them in the same manner and under the same rules and regulations as guardians ad litem are appointed in proceedings for partition of real estate, and the judgment and proceedings of such court in any such suits shall be as binding on such minors as if they were over the age of eighteen years.
§ 429.200, RSMo