A motion is an application to the court for a specific court order within the confines of an existing case. In order to amend the original complaint you would need to file an amended Complaint if you initiated the child custody action originally.A party can amend a pleading once, as of right, "within twenty days after its service, or at any time before the period for responding to it expires. Ask for leave to amend, attach a copy of the proposed amended complaint to your motion, and show affirmatively why the other side cannot claim any prejudice. To ask the judge to set aside your default judgment, you must file a "motion" (a formal written request) with the court. Fill out the generic motion form below and title it "Motion to Amend Complaint. Motions must be filed at least five (5) business days before the return date of the motion. Motion to Amend Judgment - MAMJ (CIV). MAPO. Motion to Appear as Out of State Counsel - MAPO (CIV). MACO. Motion and Affidavit to Show Cause for Violation of TPO - MASC (FAM).