publish_to_groups
The
publish_to_groups permission allows your app to post content into a Group on behalf of a person if they’ve granted your app access. The allowed usage for this permission is to allow people to publish content from your app to their Facebook group or to help people manage the content published to their group. You may also use this permission to request analytics insights to improve your app and for marketing or advertising purposes, through the use of aggregated and de-identified or anonymized information (provided such data cannot be re-identified).