Applying for a certificate on behalf of someone else is exactly the same as applying for your own certificate, except that you need to prove that you're authorised to do so.
You need to provide:
- Proof of your identity
- A letter from one of the parties to the marriage/relationship authorising you to access their record. The letter includes the authorising person’s:
- Address
- Daytime telephone number
- Signature.
- Proof of identity of the authorising person.
Once you've got this documentation organised, follow the normal process to get a marriage certificate.
You don't need to get authorisation if you're applying for a certificate where the marriage or relationship registration took place more than 60 years ago and both parties are deceased.