You can add new routines to an existing playlist.
Follow the first few steps in "Creating a Playlist" to select the routines and access the playlist dialog box.
When the playlist dialog box appears, from the left pane, choose Existing Playlists.
From the drop-down list under Existing Playlists, select the playlist.
Follow the remaining steps from "Creating a Playlist" to define the routines and set the execution order.
Click Save to modify the playlist with the new routines.
You can also add to any playlist with the Add to Playlist option available from the menu on any routine tile.