I know the following is complicated, but I've tried to be as clear with my questions as my limited knowledge allows. As much as possible, I want to ensure that changes I make to the MARC-relevant data after it's all stored in Koha will make it back into any MARC records later exported, assuming the export functions are fixed in future revisions. I'm downloading MARC records with MARCedit and BookWhere, and preparing them in .mrc files to later import into the Breeding Farm. Do all the MARC fields existing in my records need to be linked to the non-MARC fields correctly first? Are all the data from the MARC records stored in the MARC tables "as is", even for those fields that have a -1 in the links pages? In other words, please confirm that "-1" just means that they don't display on the data-entry screens. What if I make changes to these mappings after the import into the Breeding Farm, but before Biblios and Biblioitems have been created? Please confirm that importing into the Breeding Farm doesn't create any records in the Biblio or Biblioitems tables. And what needs to be done if changes in the links are made after Biblios and Biblioitems have been created? In either case (is the answer the same or different between the two?), will the data stored in the non-MARC fields then get copied to the MARC fields? Will the data in the MARC fields that used to be linked to the non-MARC fields still be in those MARC fields? In other words, does switching a link *move* or *copy* the data between the MARC fields? Related question - if I later find more accurate/complete MARC records for existing biblio/biblioitems, import them into my Breeding Farm, choosing "overwrite" when Koha lets me know I already have that ISBN - Can I then update the relevant MARC fields for the already existing biblio/biblioitem records from the data from that new Breeding Farm record? Or do I need to make changes to existing records manually? Thanks in advance for your help Hans