In California, divorce modification is possible, but only certain parts of the divorce decree can be changed. Fill out form FL300 Request for Order to supply details of the requested change.The law permits parents to modify child custody and visitation judgments at any point after the marriage dissolves. Either parent or the child's legal guardian can ask for a change (called a "modification") to increase or decrease the amount of court-ordered child support. File a Request for Order: Use Form FL300 to file a Request for Order with the court that issued the original custody order. To initiate a custody modification, you will need to complete and file specific custody modification forms in California. Absolutely. You can file a request for hearing to modify custody. Just be sure to attach the existing court order re: custody. To initiate a custody modification, you will need to complete and file specific custody modification forms in California. Fill out the necessary forms.