S.D. Codified Laws § 55-15-4
If any trustee desires to (i) convert an income trust to a total return unitrust, (ii) reconvert a total return unitrust to an income trust, or (iii) change the percentage used to calculate the unitrust amount and the method used to determine the fair market value of the trust but does not have the ability to or elects not to do it under the provisions of §§ 55-15-2 and 55-15-3, or in the event the trustee receives a written objection within the applicable period, the trustee may petition the court for such order as the trustee deems appropriate. In the event, however, there is only one trustee of such trust and such trustee is an interested trustee or in the event there are two or more trustees of such trust and a majority of them are interested trustees, the court, in its own discretion or on the petition of such trustee or trustees or any person interested in the trust, may appoint a disinterested person who, acting in a fiduciary capacity, shall present such information to the court as shall be necessary to enable the court to make its determination.
SDCL 55-15-4