Hi
Thanks for the pointers.
Final solution:
My Documents BO:
Documents.Document the document object
Documents.Title the full file system path where the document should go as specified in Document
Rule when Documents created:
FIND ALL SystemSettings TAKE BEST 1
ThisDocuments.Title=SystemSettings.DocsPath+FILE_NAME(ThisDocuments.Document)+'.'+FILE_EXTENSION(ThisDocuments.Document)
When I Add a new Documents BO, upload the document, then click on Create, the path is set. The system does the rest in saving the file to correct location 🙂