Indiana Code Title 29. Probate § 29-3-11-3

Sec. 3. (a) If a guardian has been appointed, all actions between third persons and the protected person seeking to charge or benefit the protected person or the protected person's property shall be prosecuted by or against the guardian or person acting under a protective order to represent the interests of the protected person in the action.  All process relating to that action shall be served on the guardian.

(b) In the case of a claim against the guardian or person acting under a protective order personally, the guardian or person acting under the protective order may be sued both as guardian or person acting under the protective order and in the personal capacity of the guardian or person acting under the protective order in the same action.

(c) If an action was commenced by or against the protected person before the appointment of a guardian for the protected person, the guardian upon appointment shall be substituted as a party for the protected person.  If the appointment of the guardian is terminated, the guardian's successor shall be substituted as a party to the action.  If the protected person dies, the protected person's personal representative shall be substituted.  If the protected person is no longer a minor or incapacitated person, the protected person shall be substituted.