Every marriage of a stepfather with a stepdaughter or a stepmother with a stepson is null and void from the beginning.
S.D. Codified Laws § 25-1-7
Marriage with stepchild void
Source: SDC 1939, § 14.0106 (2).
Official source: South Dakota Legislature. Reproduced from public-domain South Dakota statutes; confirm against the official source for the current text. Not legal advice.