I would like to prevent an author from overwriting/canceling inheritance for one field in a component dialog on a page that has been rolled out using LiveCopy from the master site.
Is this possible? Is there a property I can add to that dialog field that would prevent the author for overwriting it, meaning it will always inherit from the master site?
Not sure but you could try to add "fieldEditLockMode" on that property and test it out.
Per this thread/user, it should do the trick as you expect ---
Re: Field Level Inheritance - MSM
I found the property "fieldEditLockMode" in this article: aem - CQ5 - Cancel individual property inheritance of a Live Copy component - Stack Overflow. Adding this to the component dialog let the small locks appear in front of the field in the dialog. But when I cancel the inheritance of a field, changing the content, close dialog and rollout again from blueprint the lock is closed and content is snyced.
Breaking inheritance on component field level is not supported in Touch UI, but in Classic UI it is.
Not sure why, because it's a common use case imho - we have used it on several sites and it makes editing less effort (e.g. you can keep inheritance for an image, but just override the text field).
I do not believe this is supported at the dialog field level.