Idaho Code § 11-724
If the garnishee shall allege in his answer that he is indebted to the judgment debtor, but declare his belief under oath that the debt has been assigned to some other person, while naming such person, and the judgment creditor shall file a reply, denying the fact, or the force and validity of the alleged assignment, the court shall thereupon make an order requiring the alleged assignee to appear, on a day to be therein named, and show cause why the alleged assignment should not be disregarded. Such order shall be served upon the supposed assignee, if within the jurisdiction of the court, at least fifteen (15) days before the return day thereof. But, if he cannot be found, or is out of the jurisdiction of the court, he may be brought in by publication as in other civil cases; provided, that the order shall be published instead of the summons, and that such publication need only be made for three (3) weeks successively, and that the last insertion thereof need not be more than fifteen (15) days before the return day thereof.
Idaho Code § 11-724