Is there a term for the sibling of ones son-in-law or daughter-in-law? Real-life example: The composer Dohnanyi had a son who married a sister of Dietrich Bonhoeffer. So Dohnanyi was the father of Bonhoeffer's brother-in-law, or the father-in-law of Bonhoeffer's sister.
Is there an accepted term for this relationship?
With respect to Dohnanyi, Dietrich Bonhoeffer could be referred to as:
Relatives through marriage are generally known as "affines" or "in-laws", and only the close relationships have a specific term.
This is only for English. There may be one or more other languages that have a term for this relationship.
Steve Morse's relationship calculator shows that there is no blood relationship and no English term.
