She has been a wonderful daughter-in-law to our family for many years.

daughter-in-law 是由 daughter（女儿）和 in-law（法律上的）组成的复合词，字面意思是"法律上的女儿"。 in-law 这个后缀表示"通过婚姻关系形成的亲属"，比如 brother-in-law（姐夫/妹夫/小叔子等）、mother-in-law（婆婆/岳母）等。 daughter-in-law 特指"儿子的妻子"，即"儿媳"。