My mother passed away many years ago and since then my father has remarried. He is now in a nursing home and my stepmother has moved out of their home to a senior living. My stepmother has 3 children from a past marriage. I have 2 siblings. I am worried that when my father passes away, my stepmother will get everything. Then when she passes away her children will get everything that was my fathers. His own children will not get anything. What can be done to avoid this?