As I mentioned a while back, my great-grandfather, George Augustus Keene, married Lydia Thompson soon after the death of his first wife, Ellen Piper Keene.
Ellen had passed away at age 40, not too long after the marriage of her and George’s daughter, Ellen Augusta. Daughter Ellen had married William Edwin Thompson in 1874; mother Ellen passed away in 1875.
William Thompson had a younger sister, Lydia.
Yes, that Lydia.
A year and half after the death of Ellen, George married the younger sister of his son-in-law. George was 42; Lydia was 25.
So, George’s wife was his son-in-law’s sister, but also his son-in-law’s mother-in-law.
Daughter Ellen’s step-mother was also her sister-in-law.
Ellen and William’s children’s grandmother would also be their aunt.
It reminds me of the old song, “I’m My Own Grandpa.” It’s worth a Google.