The county attorney or authorized attorney, acting for or on behalf of the State of Nebraska, may intervene without leave of the court in any proceeding for dissolution of marriage, paternity, separate maintenance, or child, spousal, or medical support for the purpose of securing an order for child, spousal, or medical support, modifying an order for child or medical support, or modifying an order for child support as the result of a review of such order under sections 43-512.12 to 43-512.18. Such proceedings shall be limited only to the determination of child or medical support. Except in cases in which the intervention is the result of a review under such sections, the county attorney or authorized attorney shall so act only when it appears that the children are not otherwise represented by counsel.