Mine are older, 15 and 12. They know what STBXH has been up to. The younger one treats him fine on the rare occasion when he comes for visitation (he's out of state). The older one will have nothing to do with it. He doen't get it and is sure I've turned them against him. Actually I try to encourage them to maintain contact, but they are not that keen to share things with him. He's paranoid and refuses to take any responsibiity for his behavior, so blaming me is easier than blaming himself, or making a real effort with his kids.