I wouldn't want to attend if I didn't know someone personally. I would feel insulted if strangers popped up at a loved one's funeral and told me they were sorry for my loss. They didn't know my loved one, so I think it would just grate on my nerves, which of course would already be fragile. If I were attending for someone that Rob knew, and I didn't know, then it would be different, because I would be supporting my husband, as opposed to the family, and I could offer condolences there through his relationship with the victim... ("I'm so sorry for your loss, my husband thought the world of....")