That sucks...Have you ever talked to your brother about it? I guess the best thing you could do is keep in touch/talk to your nephew, so he knows at least you haven't forgotten about him.
She wouldn't give it her because she "wasn't going to try and keep the relationship alive", or some crap like that. My nephew then called his Gran and asked for the address. The reply he received? "I'll have to call him and ask if that's okay first."
^ That part really sucks. It's his kid, you know. Even if your brother isn't trying, his son is and they should try to help him.
Poor kid really.
x