Hi Andrea,
These may not be the best options but a few ideas come to mind.
1) Data Generalizations field at bottom of Occurrence Record Editor (this field however is not viewable via Public Display you must be an editor to see it)
2) Identification Remarks, probably only useful if the IDs with which they are associated are 'current' and won't ever change
3) Location Remarks, Description, or Occurrence Remarks might be valid if the notes in the notebook carry this type of information.
4) Create a 'version' of the notebooks as an exsiccati in the portal and link specimen records internally within the portal.
5) Co-opt the Genetic Resources panel under Linked Resources tab.
1-3 would be easy to achieve as a batch update with a Skeletal File Import option with the caveat that option 1 will not show on Public Display of occurrence records.
4 is probably ridiculous and impractical
5 is what the community needs. I wonder how difficult it would be to request some Symbiota code to be adjusted by changing "Genetic" to "Extended Specimen" so that the Panel Title reads "Extended Specimen Resources" and add a picklist field to include 'type of resource' with options for a) Genetic, b) Field Notes or Archival Resource, c) some Natural Heritage Program Database, d) any other extension of the specimen. I think the functionality exists within this Genetic Resources panel, it's just branded as "Genetic".
Or clone the omoccurgenetic table and name it something like omoccurextended.
Finally, not sure how this table might be batch updated.
I'm curious to hear what others have to say. Several years ago we simply reversed the entire process and built an entirely separate site that focused on journals and included links to specimen records in Symbiota. Ideally, those outlinks would reciprocate to the records in the related environments.
Best,
Herrick