Viewpoints can be organized into folders, as necessary.
Click Viewpoint tab > Save, Load & Playback panel > Current Viewpoint drop-down > Manage Saved Viewpoints.
This opens the Saved Viewpoints window, and makes it the active window.
Right-click an empty space in the Saved Viewpoints window, and click New Folder.
Type in a new name, and press Enter.
Drag the required viewpoints into your new folder.