Arizona Rules of Family Law Procedure
Rule 33. Third-Party Rights and Other Claims in an Existing Action
(a) Third-Party Rights. A person other than a legal parent may petition to intervene in an existing action pursuant to A.R.S. § 25-409.
(b) Intervention by the State. The State may intervene in an existing action pursuant to A.R.S. § 25-509.
(c) Other Parties or Claims. Any other request to assert a counterclaim, a third-party claim, or for joinder of parties, interpleader, or intervention, must be made according to the procedures provided by Rules 13, 14, 18, 19, 20, 21, 22, and 24 of the Arizona Rules of Civil Procedure.