Perhaps I've done it wrong.
They haven't done anything romantic but she tells him dirty jokes all the time but they are not listed as family in the relationships panel. Well, they don't have that little family icon thingie.
Make sure to have a check in the box Family that's under Known to the right. You want a check on both of them. And if I was you, I"d make the relationship Aunt to Nephew. (I think someone else suggested this to you also.) It's the check in the family box that will give you the family icon.