S.D. Codified Laws § 55-1B-11
The powers and discretions of a distribution trust advisor over any discretionary distributions of income or principal, including distributions pursuant to an ascertainable standard or other criteria and appointments pursuant to § 55-2-15, shall be provided in the trust instrument and may be exercised or not exercised, in the best interests of the trust, in the sole and absolute discretion of the distribution trust advisor and are binding on any other person and any other interested party, fiduciary, and excluded fiduciary. Unless the terms of the governing instrument provide otherwise, then, in addition to the powers and discretions granted to the distribution trust advisor in the trust instrument, the distribution trust advisor shall direct the trustee with regard to all discretionary distributions to beneficiaries, may direct appointments pursuant to § 55-2-15, and may exercise any of the powers and discretions granted to a distribution trust advisor in § 55-2-13.
SDCL 55-1B-11