I believe that it would depend upon your relationship with that step-parent or family. My father and my step-mother are no longer together, but they do remain good friends. I have a very close relationship with her, and still refer to her as my step-mother, she is the only grandmother that my children have from my side of the family, and continues to co-grandparent with my dad. I am also close to my step-sisters and their children, and still refer to them as my nieces and nephews, and my children refer to them as cousins, so in my case, yes, if my father passes away before my stepmother, I would still be in contact with my former step-family. By comparison, my sister couldn't wait for my dad and step mother to separate, and does not remain in contact with anyone in the family, and does not allow her son to call my step-mother grandma.