You can also expand and make changes to your selected feature by adding additional files and folders to it. For e.g. if you select a file or folder from the 'Outgoing Dependencies' panel, right click on it and select 'Map to Active Feature'. It is important to note that only files which have a relationship to the feature will be transferred from the folder to the feature. All other files not related to the feature will remain in the folder and will not be transferred. If you now look in your 'Feature IO' panel you will see that the feature has changed and that the files you mapped to the feature are now part of the feature.
JITTAC Adding Elements to a Feature
Adding Elements to a Feature