Hi,
Send somebody to registrar of marriages office, they can meet some body there who help to file for marriage certificate. They will get you language of affidavit ,which is basically your permission to your wife to apply for marriage certicate, you should type here in usa,get it notralised in usa and send back to your wife. She will need marriage proofs ie photos,marriage invitation cards,affidavits by 2 relatives from your side and from her side, may be some more evidence of marriage. This shpuld work because this information was sent to me from (Punjab) India some years back