SDCL § 15-9-15: Service by publication on unknown parties.

When it is made to appear by affidavit, made by or on behalf of the plaintiff, that there is reason to believe that there may be unknown persons, whether personal representatives, devisees, legatees, heirs, or creditors, of any person having an interest in the subject matter of the suit, or any other unknown person having claim of any character which might be adversely affected by the judgment to be rendered in the suit, the court may grant an order for the service of the summons upon such unknown persons by publication.