The marriage certificate can be again reissued by the registrar office in Delhi. An application has to be given for the same. 

That marriage certificate is to be apostilled.

You can get it through office of sub registrar of marriages easily

You need certified copy of marriage certificate 

application has to be made to marriage registrar office which issued 

the marriage certificate 

There's no necessity for reissue of marriage certificate if the marriage was already registered before a marriage registrar. 

You may have to apply for certified copy of the registration certificate before the concerned registrar. 

You can authorize anyone on your behalf for completing this task in your absence. 

Marriage certificate, birth certificate, sale deed etc. is public documents, any of your friend furnishing particulars of marriage like name of parties, date of marriage, certificate number can obtain a certified copy from Registrar of Marriages, there is  no issue. MEA may insist on presence of parties as it has to ascertain who are the parties. Your relative in Delhi can very much obtain a certified copy which is as good as original. What MEA  can do is also done by Indian Embassy/Consulate, they have equal power and duty towards Indian citizens residing abroad. A marriage office is there in every Indian Embassy abroad, you can request him to help.

Re-issue of the marriage certificate is possible only if you have lost the original one.

File a Police Report that you have lost the original one, and then apply for issuance of a certified copy/duplicate copy of the original. You will need to produce the photo of the original marriage certificate, Hope you have retained the same. 

Dear Client,

                  You may visit the office of the marriage registrar concerned, submit an application for issue of certified copy of the marriage certificate by complying with the formalities then you may get a certified copy of the original marriage certificate from the marriage registrar in India.

Thanks & Regards

You can easily get duplicate marriage certificate for marriage which was even registered 30 years back.

Contact any experienced local lawyer for the same.

Attestation from ministry of external affairs can be done once the duplicate marriage certificate document has been received. It takes around 1 week maximum for the documents to be attested from MEA.

- If the marriage was already registered before the Marriage registrar, then the registrar cannot re-issue the same certificate , but you can get the certified copy the said certificate from the same office. 

- Hence, your relative can approach the office of the registrar where the marriage was registered , after moving an application for getting certified copy the marriage certificate.