Rule 9 - Service of Legal Papers; Proof of Service(a) Service. Except when these rules provide otherwise, copies of all papers filed in a mental retardation case shall be served upon the individual who is the subject of the proceeding, his or her attorney, advocate, and parent or guardian (or other petitioner), and the Office of the Attorney General. Service may be made by first class mail.(b) Proof of service. Proof of service of papers served pursuant to these rules shall be accomplished by means of a certificate of service on the last page of the paper served. This certificate shall show the date and manner of service and the names and addresses of all persons served. Failure to make proof of service shall not affect the validity of such service. The Court may at any time allow the proof to be amended or supplied, unless to do so would result in material prejudice to a party.