The good news is that you can put the doc in both folders. Here's how:
- Open Google Drive (not Google Docs for this-- Drive is the organizational app).
- Click on the file to select it (don't actually open it). You can even select multiple files with Ctrl-click, if desired.
- Press Shift-Z.
- You will then be asked where you want to add the file. This is not the same as Move To.., because you're not moving it.
- Note that this does not make a copy of the file. It's the exact same doc; you can open and edit it from any of its folders.