Idaho Rules of Civil Procedure Rule 4(d)(3). Service Upon Infants and Incompetents.
Upon a minor less than fourteen (14) years of age, service shall be upon the guardian if one (1) has been appointed, and if there is none then upon either the father or mother, and if neither guardian, father or mother be found within the state then upon any person having the care and custody of such minor, and unless the court otherwise orders, also upon the minor, said service to be in the manner set forth in subdivision (2) of this rule. Upon an incompetent person who has been judicially declared to be of unsound mind or incapable of conducting the incompetent person's own affairs, service shall be had upon the guardian if one (1) has been appointed in this state, or if there is none by service upon a competent adult member of the family with whom the incompetent person resides, or if the incompetent person is living in an institution then upon the chief executive officer of the institution, or if service cannot be had upon any of them, then as provided by order of the court, and unless the court otherwise orders, also upon the incompetent. If any of the parties upon whom service is directed to be made is a plaintiff, then service shall be upon such other person as the court may designate.