SDCL § 29A-2-503: Writings intended as wills, etc..

Although a document or writing added upon a document was not executed in compliance with § 29A-2-502, the document or writing is treated as if it had been executed in compliance with that section if the proponent of the document or writing establishes by clear and convincing evidence that the decedent intended the document or writing to constitute (i) the decedent's will, (ii) a partial or complete revocation of the will, (iii) an addition to or an alteration of the will, or (iv) a partial or complete revival of a formerly revoked will or of a formerly revoked portion of the will.

Source: SL 1995, ch 167, § 2-503.