How to deal with my dad? Coming up to visit before baby is born...?

I understand that in his home its his place to do whatever he wants. But in your own home, those are your rules. If he tries to smoke in your home, then i would ask him to leave if hes not going to listen to you. Especially around your baby. If he loves you and his grandaughter like he says he does, then he should have no problem stepping outside to smoke. If he smokes around the baby after shes born, she could develope asthma, she already has a risk of getting it because of genetics, and that could make it worse, she could get frequent ear infections, etc. Put your foot down and tell him how it is. I wouldnt stand for it, not when it could effect my baby's health.