If someone moves to another state after his or her case is over (e.g. from Idaho to Illinois) and then later wants to commence another action (related to that same case), they generally have 2 options: 1.) return to the original state to file the action; or 2.) petition to the court in that state to commence the action.
What you decide will largely depend on the facts of your case, including but not limited to whether Illinois has the authority to hear the case. This will be based on a variety of factors that your lawyer should discuss with you. However, if both parties are now living in the new state, the likely choice will be pursuing the action in that state, and that means the first step will be enrolling the “foreign judgment.” The foreign judgment means the judgment of the state from which you moved.
Whether it is a custody judgment or a judgment for dissolution of marriage, or your goal is to modify or enforce the judgment, Illinois law provides that foreign judgments shall be enrolled first. Your lawyer can assist you this relatively straightforward filing that will begin your case.