At a party's request, the court must order witnesses excluded so that they cannot hear other witnesses' testimony. Or the court may do so on its own. But this rule does not authorize excluding:
(a) A party who is a natural person;
(b) An officer or employee of a party that is not a natural person, after being designated as the party's representative by its attorney;
(c) A person whose presence a party shows to be essential to presenting the party's claim or defense;
(d) A person authorized by statute to be present; or
(e) A victim of a crime and his parent or guardian following the victim's testimony.