Sentence:  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&mdash;the <WSD>wife-in-law</WSD>, or the husband-in-law. 
Meaning of the word marked with <WSD> tags:  Another wife of one's husband. Typically used in cases of divorce and subsequent remarriage for one's husband's ex-wife, but sometimes used in polygamy for a co-wife.