Uncle? Cousin?

Our daughter, Marian's Finny was here to help us celebrate Christmas.  He had his own stocking hung by the fireplace, just like the boys.  My question is this:  If Marian is our daughter and Finny is her "child," then Andy and Roy are Finny's uncle?  Right? Since Finny weighs 40 pounds, and the boys weigh under 20 pounds, they would rather think of him as a "cousin" than an uncle.  Besides he doesn't want to be "uncled" by two fluffs.  He just wants to be left alone for the most part.