I have filed immigration for my father. He was born in Karachi (Now in Pakistan) before the partiti0on of India/Pakistan. My father now lives in India. His birthplace in Indian passport and school leaving certificate indicates "Karachi". We have obtained affidavits of two relatives as an evidence of birth. USCIS needs "Non Availability of Birth Certificate" from government authority along with affidavits. Where should we get this "Non Availability of Birth Certificate". Are there any options if we cannot get this letter?