S.D. Codified Laws § 29A-3-410
If two or more instruments are offered for probate before a final order is entered in a formal testacy proceeding, more than one instrument may be probated if neither expressly revokes the other or contains provisions which work a total revocation by implication. If more than one instrument is probated, the order shall indicate what provisions control in respect to the nomination of a personal representative, if any. The order may, but need not, indicate how any provisions of a particular instrument are affected by the other instrument. After a final order in a testacy proceeding has been entered, no petition for probate of any other instrument of the decedent may be entertained, except incident to a petition to vacate or modify a previous probate order and subject to the time limits of § 29A-3-412.
SDCL 29A-3-410