Getting marriage certificate

Better you can approach the sub-register office, there will be few Document writers near sub-Register office, they will help you to get the Marriage certificate ASAP.

The marriage registration certificate can be received from the office of Registrar of Marriage in whose jurisdiction the marriage took place.
Certain forms and formalities need to be completed as per procedure, it would be issued on payment of required fees.

A Marriage Certificate is the proof of registration of a marriage. Needed to prove that you are legally married to someone, for purposes like obtaining a passport, changing your maiden name, etc.

 Where to apply for Marriage Certificate?

You can apply at the SUB REGISTRAR's OFFICES

i) Sub Registrar's Office (Bombay) Old Custom House, Shahid Bhagat Singh Marg, Ground Floor, Fort, Mumbai 400 023.

 ii) Sub Registrar's Office (Bandra), Andheri & Borivaii Taluka, MHADA Building, Ground Floor, Kalanagar, Bandra (E), Mumbai 400 051.

 iii) Sub Registrar's Office (Chembur) Kurla Taluka, R.C.V. Marg, Near Rationing Office, Administrative Buildings, Ground Floor, Chembur, Mumbai 400 071.

Document Required for a Marriage Certificate

1) Age proof Bride & Bridegroom Age proof: Leaving Certificate/ Passport /Birth Certificate/ Domicile Certificate OR PAN Card.

2) Residential Proof of Bride & Bridegroom: Ration Card /Passport/ Election Card/ Light Bill and Telephone Bill of own name.

(3) Witness Proof: - Ration Card/ Passport/ Election Card/ Driving License/ Govt. Identity Card.

4) Wedding Card

5) Rs. 100/- Court Fee Stamp

6) Photographs of both Bridegroom / Bride.

In case of non-availability of Wedding card Rs 100 Stamp Paper Affidavit of both husband wife and three witnesses is required

How much does it cost for a Marriage Certificate?

Rs. 100/- is charged as application fee for Registration and Rs. 150/- is charged for Solemnization, it varies from state to state.

Fees for a Marriage Certificate vary from state to state. Please check at your nearest Registrar's office.

- See more at: https://www.ipaidabribe.com/how-to/how-get-marriage-certificate-mumbai#gsc.tab=0

Do not be misguided by local lawyer's unacceptable advise.  You do not have to convert or your wife need to convert herself.  You can get your marriage registered under the provisions of  Special marriages act itself. The procedures to be followed in this regard can be found dangling on the wall or pasted in the notice board outside the office of sub-registrar of your local jurisdiction.  You may comply with the requirements, you do not require a lawyer to assist you in this connection. For further details you can follow the advise rendered by Adv. Majeed above.

Please follow the guidelines of Ramacharya. It is practical and I got succeeded in my personal case