S.D. Codified Laws § 10-25-6
If any of the persons on whom notice is required to be served by §§ 10-25-3 and 10-25-4 is deceased, the notice shall be served on the decedent's personal representative, foreign or resident, or on the resident agent of a foreign personal representative, if any are known to the certificate holder. If no such person is known, the notice shall be served on any known heirs and beneficiaries of the decedent, in the same manner as if the heirs and beneficiaries were owners of record. For any unknown heirs and beneficiaries of the decedent, notice shall be served by publishing the notice as provided in § 10-25-5 and designating such unknown persons as the unknown personal representatives, heirs, and beneficiaries of the deceased. The fact of whether the decedent, the decedent's personal representative or resident agent, or any heirs and beneficiaries are known or unknown shall be sufficiently established for tax-deed proceedings by the affidavit of completed service of the certificate holder or the tax certificate holder's agent or attorney conducting the proceedings.
SDCL 10-25-6