Obc non creamy layer

I have recently got an interview call letter for a prestigious government service. I applied as an OBC candidate as in my home state i.e. Rajasthan we are included in the central list of OBCs. I was born in Rajasthan in 1991. Since then I was living in Rajasthan and all my schooling has been from the same state. I would like to mention here that I have never lived with my father but my mother who passed away way back in 1992. Since then my maternal grandfather has taken care of me. But there is no legal procedure followed e.g. adoption. However, my father is an original resident of Haryana where we are not considered as OBC. Now I got a letter from the concerning authority that I have to produce a certificate from the place where my father originally belongs to. The competent authorities in my father's birth place cannot issue the certificates as I am bonafide resident of Rajasthan. I have all the proofs that I am an original resident of Rajasthan like my birth certificate, my school fees and marksheets from class I to Class XII, ration card, driving license etc. Kindly, guide me what to do. Regards