In California, a factual mistake included on the face of the marriage license can be corrected by filing an Affidavit to Amend a Marriage Record with the County Clerk's office in the County that issued the marriage license.
Amend has basically the same meaning in common usage as it does in the legal arena. When a legal document is amended, it is edited, corrected or changed in some way.
You wouldn't be able to just backdate a marriage license - b/c it wasn't legally issued until it was issued.
Amending marriage certificates is done in order to correct errors found on the original certificate. Amendments are not used to make changes on the document. Examples of errors include: spelling errors, grammatical errors, adding information to empty "blank" lines.
Contact the Division of Vital Records for detailed instructions and forms. Complete the required forms. Prepare a formal correction request letter. Submit the request along with documentation and fees. Wait for the processing time. Verify the corrected marriage certificate upon receipt.
You can only add a new middle or last name to your marriage license if the name is related to your or your spouse's current or former name. For example, you want to change your last name to your spouse's last name. Or, you want to combine your last names.