Any of the powers enumerated in § 55-1B-6, as they exist at the time of the signing of a will by a testator or at the time of the signing of a trust instrument by a trustor, may be, by appropriate reference made thereto, incorporated in whole or in part in such will or trust instrument, by a clearly expressed intention of a testator of a will or trustor of a trust instrument.
SDCL 55-1B-8