When editing a particular profile, if you are on the Trusted List, there should be an Edit link next to the existing Last Name at Birth. If you are not on the Trusted List, you can contact the profile manager to be added to the Trusted List, if desired, or to request the profile manager make the correction. It's probably a good idea to communicate via profile comment or private message in advance of making such a change and to share your source documentation in case there are conflicting sources.