(1) Except as authorized for proceedings brought under chapter 13.34
RCW, or chapter 26.50
RCW in district or municipal courts, a child custody proceeding is commenced in the superior court by a person other than a parent, by filing a petition seeking custody of the child in the county where the child is permanently resident or where the child is found, but only if the child is not in the physical custody of one of its parents or if the petitioner alleges that neither parent is a suitable custodian. In proceedings in which the juvenile court has not exercised concurrent jurisdiction and prior to a child custody hearing, the court shall determine if the child is the subject of a pending dependency action.
(2) Notice of a child custody proceeding shall be given to the child's parent, guardian and custodian, who may appear and be heard and may file a responsive pleading. The court may, upon a showing of good cause, permit the intervention of other interested parties.
(3) The petitioner shall include in the petition the names of any adult members of the petitioner's household.