I can not answer your question specifically to the laws of Utah as I am not lisenced in that State. In most jurisdictions, a failure to pay child support does not allow the other parent to deny you visitation. It is unclear if you have specific court order for the amount of visitation. If you do not have specific times for visitation, I suggest that you file a Motion to Modify the visitation schedule. You can also ask the court to set a telephone contact schedule if that has been a problem. If you have a specific schedule and you are being denied that custody time, file a motion to enforce the order of visitation. This would be a Motion for Contempt or Motion for Family Access. The court may order additional time with the children to make up the time that has been missed. Further, if you have had a significant reduction of income and the reduction was involuntary, you should file a Motion to Modify the child support amount. The standard for a Modification of Custody (as compared to modifying visitation only) is often very high. The Motion to Modify custody is very fact driven and there really is not sufficient facts prensented to provide a full accessment of your case. Your oldest child (perhaps the oldest two chldren) is probably old enough to express his/her wishes with regard to custody. However, the child's wishes are really only one factor. The fact that the step mother has a mental disorder could be helpful if the disorder affects the children. Finally, the fact that you have been denied custody would be a factor in your favor. However, the fact that the children have been in his custody and this proposed change would be very significant considering the distance that you would relocate the children are substantial hurdles to overcome. One final note, if you are behind a lot of money in child support, you need to be aware that most states have criminal nonsupport provisions that make it a felony if you exceed a specific amount of child support arrears.