"When I have children"

Dectski, I would imagine that this is something that you could work out with everyone as the situation arises. If your adad has been unpleasant to you about adoption issues in the past then you might need to be careful about watching his interactions with your kids, and have an idea of how you will handle the kinds of things he's said to you if he says them to your kids. Kids will believe you if you say that something someone said was mean, especially if you them offer a better explanation or idea. You might also want to limit contact with your adad, depending on how bad it gets.