My Brother-in-law has a son from  his wife's first marriage, the Son has a child. What relationship is the Child to me (or my wife)? No formal adoption papers were ever started. To complicate this whole thing - - - Son of wife's 1st marriage has 2 children, each child has  a different mother. My F-I-L states they are "His left handed Grandchildren' Anyone with a better name for this relationship? John