File changes to child support if both parties agree to the change, Mass. You must file the Affidavit in cases involving the care, custody, visitation, or change of name of a child.Go to the court that made the child support order. This can involve filing a complaint for modification in the probate and family court, particularly when seeking to adjust child support or custody arrangements. In Massachusetts, you can file a Complaint for Modification. Facing a modification of family court orders case? Whether petitioning or contesting, Miller Law Group's Massachusetts modification attorneys can help! We're here to guide you through the process of post-divorce modifications involving child custody, child support, and alimony orders in Massachusetts. To change a custody order, you also need to file in Probate and Family Court. In Massachusetts, a divorce modification refers to any change made to the terms of a divorce agreement postfinalization.