The obstacle that you will have is that unless you contrive some kind of secret code that users need to enter, there is not a way to control who can do edits as if you open up your app to everyone on the internet, then everyone on the internet can make edits. There is not really a secure was to allow that kind of access and control it hen the users do not have their own userids.
You maybe need to allow users just to to view and then fill out a form to request changes. An internal user can then vet the changes perhaps associate them as a child to the "LinkedIn" record and click a button to copy the changes to the "LinkedIn" record.
