My father's second wife is a non Jew, he has few children with her, which we have never seen. He lives in diffrent country for many years. There is no contact or relationship. MY mother and my sister and brother are some religious to very religious. I would like to know my father’s sin will it be upon Us and our children G-D forbid? and what can I or We do to change that?

The Torah teaches that when a child does not continue in the sins of his fathers, he is not punished for his father's sins. Lead a good and productive Jewish life and through your merit, your father may also benefit.