The Koha API allows for existing records to be replaced/ overlaid wholesale with data provided.
It would be great to have the option of updating records as well, i.e., changing only data/ fields that are included in a source file while preserving all data/ fields not in the source file.
This would require a means of identifying fields that are protected from overlay on import.
(In reply to Cab Vinton from comment #0)
> This would require a means of identifying fields that are protected from
> overlay on import.
Have you looked at "Bug 14957 - Write protecting MARC fields based on source of import"?
*** This bug has been marked as a duplicate of bug 14957 ***