Mo. Rev. Stat. § 474.520

The court in which a will is probated shall have jurisdiction to construe it at any time during the administration. Such construction may be made on the petition of the executor or administrator or of any other person interested in the will; or, if a construction of the will is necessary to the determination of an issue properly before the court, the court may construe the will in connection with the determination of such issue. When a petition for the construction of a will is filed, notice of the hearing thereon shall be given to interested persons.