Tenn. Code Ann. § 29-14-107: Parties to proceedings

(a) When declaratory relief is sought, all persons shall be made parties who have or claim any interest which would be affected by the declaration, and no declaration shall prejudice the rights of persons not parties to the proceedings.

(b) In any proceeding which involves the validity of a municipal ordinance or franchise, such municipality shall be made a party, and shall be entitled to be heard, and if the statute, ordinance, or franchise is of statewide effect and is alleged to be unconstitutional, the attorney general and reporter shall also be served with a copy of the proceeding and be entitled to be heard.