S.D. Codified Laws § 15-6-17(c)
Whenever a minor or incompetent person has a guardian or conservator, such guardian or conservator may sue or defend on behalf of the minor or incompetent person. If the minor or incompetent person does not have a guardian or conservator, he may sue by a guardian ad litem. The court shall appoint a guardian ad litem for a minor or incompetent person not otherwise represented in an action or shall make such other order as it deems proper for the protection of the minor or incompetent person and may make such appointment notwithstanding an appearance by a guardian or conservator. Unless the court otherwise orders, no guardian ad litem shall be permitted to receive any money or other property of his ward except costs and expenses allowed to such guardian ad litem by the court or recovered by the ward in the action until such guardian ad litem has given sufficient security approved by the court to account for and apply such money or property under direction of the court. Such guardian ad litem may with the approval of the court settle or compromise in behalf of his ward, the case in which he is appearing and any judgment entered therein.
SDCL 15-6-17(c)