Mo. Rev. Stat. § 509.470
509.470 Additional parties made defendants when required for counterclaim or ...
509.470. Additional parties made defendants when required for counterclaim or cross-claim. — When the presence of parties other than those to the original action is required for the granting of complete relief in the determination of a counterclaim or cross-claim, the court shall order them to be brought in as defendants as provided in this code if jurisdiction of them can be obtained.
(L. 1943 p. 353 § 78)