Thank you for trying to approach this in a new way. As people said, you Dad will always be your Dad, for better or worse. Klaus I am sure is not planning on "replacing" him in your heart - and the good thing about the human heart is that it expands to fit as many people as we love - and pets, too! Miraculous, isn't it? Give Klaus and Diena a chance, and think of them as new people in the neighborhood, if that makes it easier than thinking of them as "instant family!"