Attachments using seperate documents with links rather then "embedding" within a record is a real pain.
Regardless of how you choose to actually store the data, you should be able to have the UI show an attachment ONLY within the file it relates to.
If you really think that lots of people will have attachments that are linked to multiple files (which I don't), then you can build that is on the back end as well. the LEAST elegant solution is to have the Ui cluttered with additional files that more importantly clutter the search results.
Additionally, the UI for looking at attachments is so clunky: Open the record with the attachment, then open the attachment record, THEN request the download/ display.
At a MIMIMUM, why not have a search setting which allows search to have selected categories turned OFF....
Thank you for taking the time to share this feedback! I think this comes down to personal preference too: you could argue that having all the Documents grouped in one category helps because everything is in one place rather than spread out over your items. I can see where you are coming from though!