You can add a whole list or titles from the list to your Watchlist or other created lists. To copy the list titles, take the following steps:
1. Navigate to the list
2. In the right hand of the list, click the third icon for the compact view
3. Click the titles you want to copy over or click the top box to select all
4. In the field "Copy To", select the list to copy the titles to and click "Go"