To add a Paper doc to an existing project or folder:
- Open the doc you want to share.
- Click Invite.
- Click Add to a project or folder.
- Navigate to, search for, or create the project or folder you want to add your doc to.
- Click Move.
Your doc has the same sharing settings as the folder or project you add it to. If you add your doc to a folder inside another folder or project, your doc has the settings of the top-most folder.