The following is from FAUQUIER FAMILIES, 1759-1799, by John P. Alcock - Stephen Pritchard,, M 3-348 [minute book 3, page 348] 1767, Indicted for marrying and cohabiting with Margret Kenner alias Pritchard, sister to his former wife, contrary to law. So, it would seem that at least in 1767, it was illegal to marry one's sister-in-law. Linda Hope