I can only speak for storing documents with DocuWare. I do not know StorageRobot, so I cannot assist you further. At some point DocuWare must be storing the documents. How you address the keyword field with your 3rd party application is a question for Docuscan.
Now, I suggest that you create a small test file cabinet with 2 fields. Invoice Number (Text field), and Dossier (Keyword field). Store a few documents manually entering multiple dossier number in the dossier field. Then look at the database. You will have a main table, and a table with the name of the keyword field.
The documents are related via the DWDOCID.
For example you have DWDOCID 100. With 2 dossiers ABCDE and WXYZ.
The keyword table is structured:
So a query to retrieve the invoice for dossier ABCDE:
SELECT * FROM [maintable] WHERE DWDOCID IN (SELECT DWDOCID FROM [keywordtable] WHERE DOSSIER = 'ABCDE')
At least this will show you the structure and how it works. Perhaps you can resolve the issue from there.
Senior Director Support Americas