This is closely related to the issue of increased costs of visitation if the parents live further from each other; in general, the costs of visitation are borne by the non-custodial parent. In this case, however, in order to spread the burden of costs evenly, you may seek that these costs are proportionately and reasonably passed on to the custodial parent. If one of the parents believes that he can move to the other side of the country just to make visitation for the other parent more difficult, it may blow back on them and, most importantly, on the child.