S.D. Codified Laws § 26-7A-100
Unless otherwise specifically ordered by the court in its order or decree, nothing in this chapter or in chapter 26-8A, 26-8B, or 26-8C gives the conservatorship of the estate of the child to any guardian appointed or changes the age of minority of a child for any purpose unless the child is a person under twenty-one years of age who is under the continuing jurisdiction of the court, as defined in § 26-7A-1, is under commitment to the Department of Corrections or is under continuing foster care pursuant to § 26-6-6.1. However, the court may appoint a conservator of the estate of a child who is under the age of eighteen years if the child is within the jurisdiction of the court and the court specifically finds that appointment of a conservator of the estate of the child is necessary and appropriate under the circumstances and is in the best interests of the child.
SDCL 26-7A-100