title: Why do parent_id and post_id have different values in facebook webhook
body: <p>When I received an update through webhooks, which came from updating the cover photo and commenting on the post created from it, the post_id was different from parent_id. However, when executed in the graph api, they both refer to the post noted by post_id. </p>
  
  <p>I'm curious to know why since from what I've noticed they (i.e. post_id and parent_id) are usually equal if the update is a comment.</p>