Obc certificate for reservation under jobs of Government of India

My father migrated from erstwhile Bihar to Jharkhand in 1970s for employment under coal india limited.I was born in 1993 in Jharkhand(erstwhile Bihar) and did my schooling here.Upon reorganization of the state in 2000 my birth place is now falls in the territory of Jharkhand.I have been living here for 25 years but when I approach state authorities here for issuing caste certificate to me for central government jobs they ask me produce the khatiyan (land record) of 1968 to establish that my ancestors lived here.None of my ancestors lived here nor do we have land record pf 1968 and therefore I am denied the benefit of reservation for central government jobs.I learnt about a DOPT circular which instructs state authorities to issue obc certificate to migrants based on obc certificate issued to their father in the state of his origin.Neither my father nor anybody from paternal side has an obc certificate from Bihar.The said circular is silent on what is to be done in such cases.We have our ancestral property and land in our native village in Bihar.If I am not issued the caste certificate by Jharkhand government can I instead get it issued from Bihar based on land record there.Will the said certificate be valid for central government jobs despite me not being ordinarily resident there as the certificate says.