If a custody plan doesn't work, can it be changed ?

Yes. The easiest way to change a custody arrangement is for you and your spouse to come up with a new plan and ask a judge to make it official. Judges often approve changes without a hearing if both request them. If you cannot agree on changes, either of you may ask a judge to make the change. The judge's decision will be based on your children's best interests. Suppose you want to take custody away from your spouse who does not want to give it up. Then you must convince the judge that you r children now would be better off with you. You may try to show, for example, that your spouse won't let you visit the children or is hiding them from you. Or you may present evidence that your spouse neglects your children. However, you should know that getting the arrangement changed may be a difficult if the children are reasonably cared for and the custody plan has been in effect for some time.