Are you just wanting to add only the surname or be part of that profile ?
Want to be Part of:
First, Request to join that profile's trusted list, once you're approved ask or add yourself as manager. This way you can edit all you want, plus share that profile with them at the same time!
No interest in the profile
Private Message the existing Manager of that profile and tell them what you know and include the source as well, so they to can verify it. Be sure to do a follow-up just in case they didn't add the correct surname ! Spelling wise.