As far as I can tell, one cannot replicate a file in the universal InBox of a database into another open database. One can drag and drop a file into another open database in the sidebar but then one has to go and sort the entries in the second database’s InBox. It would be nice to be able to replicate, move or duplicate an entry into specific folders of another open database.
I have not tried using the Sorter for this. I presume one can add folders from different databases that can then be sorted into a user’s different databases.