Terms for "Your Child's In-Laws"

We need a common word for "the parents of your son-in-law or daughter-in-law." Although English has the word affines, it's rarely used outside of such fields as anthropology or psychiatry. Other languages have more commonly used terms for "your child's in-laws," such as Yiddish machatunim or machetunim, and Spanish consuegros. This is part of a complete episode.