Mo. Rev. Stat. § 454.639

All remedies available for collection and enforcement of child support apply to medical support ordered pursuant to sections 454.600 to 454.645. The remedies established by sections 454.600 to 454.645 are in addition to and not in substitution for other remedies provided by law and apply without regard to when the order was entered. Either parent or the division may initiate modification proceedings to seek the addition of a provision for health benefit plan coverage to an existing court or administrative order, notwithstanding the requirement under this chapter, chapters 210, 211, and 452 to allege or prove a substantial and continuing change in circumstances.