Legal Question in Family Law in Missouri

Are you speaking in terms of a Dissolution of Marriage? If so, you should attempt to get a Court Order in place as soon as possible to prevent her from removing the child from the state pending the Dissolution or at least providing for whatever protection is necessary. Then, in the Dissolution case the issue of custody will be fully determined either by agreement or by the Judgte after a trial. In most cases the parent desiring to relocate will be allowed to do so and whatever arrangements for physical custody, visitation, etc. that are in the child's best interests will be ordered by the Court.