Smileless, I think what you said about pictures is very wise. If parents don't want egps to copy or share photos of their kids, they shouldn't put them out there. Another option would be to block anyone from seeing them that they were estranged from. True, that is hurtful to egps, too, but I'm just talking about how to keep their pictures private.
If dd co me (I hate to even think about that!) from herself and my gc, I would assume she wouldn't want me to be sharing any pictures of them. But maybe that is because of what Iv read in some of these threads. I might not have thought of it otherwise.
No matter what you do, once something is on the Internet, it's out there. So unless parents ask/tell the gps not to share/copy their children's photos, I don't see how they can expect them to know. We're none of us mindreaders.