I have the same problem with my father. As long as we are outside he has no problem lighting up right in front of Andrew. Now CF or no CF, I don't like the idea of either of my children being around cigarette smoke, and would think that a grandfather would have their grandchildren's health in mind and refrain. However, I am trying to remember that the addiction is bigger than he is. Sad but true. If controlling his smoking was possible, he would not be a smoker. So, I just limit our trips to his home, take the kids away when he lights up, and always follow up with a talk about why smoking is wrong. (Which I don't have to drill into them too much because they think Grandpa is stinky and "Why would he want to do that to himself?") It's too bad that something like tobacco can put such a strain on a relationship. But then again, I have never even tried smoking so I don't completely understand. I just try to control my anger and remind myself that everyone is different. You can control yours and your child's environment, you can't control your fathers. Good luck! I feel for you!