Mo. Rev. Stat. § 452.343: All judgments and orders shall contain the parties' Social Security numbers.

Notwithstanding any provision of law to the contrary, every judgment or order issued in this state which, in whole or in part, affects child custody, child support, visitation, modification of custody, support or visitation, or is issued pursuant to section 454.470 or 454.475, shall contain the last four digits of the Social Security number of the parties to the action which gives rise to such judgment or order. The full Social Security number of each party and each child shall be retained in the manner required by section 509.520.