There are several ways to add Pieces to a Project: 

• From within a Project: Click the “+” icon in the Project header and select your Piece(s) using the green checkboxes on the left
• From the Library: Click on “Edit” in the top-right corner of the Library screen, select your Piece(s) using the green checkboxes and click on “Copy to Project” in the top-left corner
• When importing a new Piece: When you create a new Piece from the Import menu, you will always be presented with the option to add it to a Project

Note: Copying a Piece from the Library or from a Setlist to a Project will duplicate it to create an independent Piece.