Mo. Rev. Stat. § 476.675
Any person who is a commissioner of the juvenile division of the circuit court, appointed pursuant to section 211.023 on October 1, 1989, may elect to transfer membership service earned under the provisions of the Missouri state employees' retirement system as a commissioner of the juvenile division of the circuit court to creditable service as a judge as defined in section 476.515, if such person makes written application to the board of trustees of the Missouri state employees' retirement system and to the state courts administrator to transfer such service prior to December 31, 1989, provided application is made prior to the person receiving retirement benefits for such service. In no event shall a person receive credit for the same period of service under more than one retirement system or plan.
§ 476.675, RSMo