Mo. Rev. Stat. § 507.210
Current with changes from the 2023 Legislative Session
If such infant defendant neglects, for one day after the expiration of the time within which the infant defendant is summoned to appear to the suit, to procure the appointment of a guardian ad litem to defend the suit, the court shall appoint some competent person to be guardian ad litem for such infant in the defense of such suit.
§ 507.210, RSMo
RSMo 1939 § 869, A.L. 1949 H.B. 2117, A.L. 1983 S.B. 44 & 45