Husband-in-law

the collection of people who would gather in either of the two houses for Christmas and Thanksgiving, and sometimes again in summer. This collection involved former mothers-in-law, former husbands, ex-wives of former husbands, and doddering uncles from distant marriages, as well as, of course, the various and sundry children and dogs (dogs-in-law as one family member calls them) of the now recombined families. In the process, I believe, we were responsible for the creation of a new American family relative—the wife-in-law, or the husband-in-law.

Source: wiktionary

"Your plan provides Browne with two charming wives and gives me but one. […]" "But, my lord," said Saunders, "doesn't the plan give Lady Deppingham two husbands? It's quite a fair division." "It would make Lord Deppingham my husband-in-law, I imagine," said Drusilla quaintly. "I've always had a horror of husbands-in-law." "And you would be my wife-in-law," supplemented Lady Agnes. "How interesting!"

Source: wiktionary