If you want to add an existing package, you can add the package by selecting the package folder in the Settings.
To add existing package to the DaVinci Package Manager, refer to the section Options | Settings - Package Folders.
You can only add packages with a Component Based Folder Structure. Other packages will not be shown in the DaVinci Package Manager.
In the classical delivery structure there exist the global folders BSW, BSWMD and Generators.
In the Component Based Folder Structure the folders exist per module in the folder Components.