California Code, Family Code - FAM § 17433

In an action in which a judgment or order for support was entered after the entry of the default of the defendant under Section 17430, the court shall relieve the defendant from that judgment or order if the defendant establishes that the defendant was mistakenly identified in the order or in any subsequent documents or proceedings as the person having an obligation to provide support.  The defendant shall also be entitled to the remedies specified in subdivisions (d) and (e) of Section 17530 with respect to any actions taken to enforce that judgment or order.  This section is only intended to apply where an order has been entered against a person who is not the support obligor named in the judgment or order.