Okay so I don't know what's going on. I made a Sim and his Brother. One Sim had 2 kids and a wife, and now their relationships are all screwed up. I can't make my Sim the uncle to the children, only B...
I tried the full edit mode, and it worked like a charm. I can edit names, tattoos, body shape, and relationships. No lag either. I guess something must be up in some people's configurations.