To modify a permanent award of custody, the court must find that a change has occurred in the circumstances of the child or his custodian, and that the custody modification is necessary to serve the best interest of the child. Such a finding must be based on facts which have arisen since the prior decree or upon facts which were unknown to the court at the time of the decree. When custody of children is once adjudicated, it is presumed that the custodian remains suitable.
Where the parties do not agree to a change of custody, and the child has not been consentingly integrated into the family of the non-custodial parent, a custody modification can only be accomplished by proving that the child is "endangered" in the current custodial environment. In practice, this means that there must be strong evidence in favor of the change of custody. Examples of such evidence are:
The standard to determine custody in the original action is different than a modification of custody. The measure in an original action, such as a dissolution or paternity case, is "What is in the best interests of the child." The measure in a modification is a much higher standard, "a substantial and continuing change of circumstances since the original decree."
In Missouri, child support is based on the combined income of the parents, the needs of the child, and the costs of child care and health insurance. In determining
whether to order child support, a court will consider: