Mo. Rev. Stat. § 527.080: Supplemental relief.

Further relief based on a declaratory judgment or decree may be granted whenever necessary or proper. The application therefor shall be by petition to a court having jurisdiction to grant the relief. If the application be deemed sufficient, the court shall, on reasonable notice, require any adverse party whose rights have been adjudicated by the declaratory judgment or decree, to show cause why further relief should not be granted forthwith.