If I bought a very expensive house for my father, should I ensure that if anything happens to him the house will return to me?

Id like to gift my father a house. My father is married to my stepmother and they have two children. Throughout the years my step mother has never treated me well. When I try to have a relationship with my siblings Im blocked or given a lot of difficulty. If I do not say anything it is very likely that my father would leave the house to his wife and children. And they will of reaped the benefits from a person they did not treat fairly. Should I just ignore this or ensure the house is returned to me?
P.S. I would not kick them out or anything. They just would not be able to sell it and get money from me.