When a 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 proceeding. The venue of said action shall be established by existing statutes; provided, however, where the action involves an individual defendant the venue shall be in the county of his or her residence or where he or she may be served with summons. If such action involves more than one such individual defendant, who reside in different counties, the venue shall be in any county where any of such defendants reside or may be served with summons. In any proceeding which involves the validity of a municipal ordinance or regulation, such municipality shall be made a party, and shall be entitled to be heard, and if a statute or regulation is alleged to be unconstitutional, the Attorney General of the state shall also be served with a copy of the proceeding and be entitled to be heard.

Laws 1961, SB 141, p. 59, § 3.