Step father's name in the passport

Respected Sir/s I was married in the year 2002 to Mr S Kukreja who is the biological father of my son. We got mutually divorced in the year 2006. My son from the marriage with S.Kukreja was a year old at that time and he is not aware about all this past. Since the day my son was born , his biological father has not even seen him once. Since then my child is been staying with me. And his biological father has no link with us. We don't even know where he is today in the world. I got remarried to Mr A. Dubey in the year 2006 and is been staying with him along with my son. My son just know that A. Dubey is his father and I, R. Dubey is his mother. His school has accepted our request and has maintained their records with A. Dubey as his father. However now while applying for his passport I need to produce his original birth certificate which has his biological fathers name, which I don’t want to get endorsed in his passport as I don’t ever want to let him know about the bitter truth, because I don’t want to snatch away his innocence because of my past. Please guide me on how can I get his step father's name as a father in his passport without letting him know about all this even in future. Views are solicited. Thanks.