I have a Drupal webform that is integrated to my CiviCRM installation and uses numerous custom fields that are associated with a particular activity type. I want to use the form to allow specific contacts to edit an activity that is part of a pre-existing case.
The contact who will be submitting the webform (contact 1) has an assigned role in the case and a relationship to the case manager. We're using Views to show some data to this contact including a link to the webform. I understand that I can pass a case ID and/or an activity ID into the form via the URL that is presented to the contact in the View, and I can see how I can do this by rewriting the output of one of the Views fields.
The question is: do I need to pass in both the case ID and the activity ID, or is it enough just to pass in the activity ID?
And what should I have as the settings for the case and activity in the CiviCRM tab for the webform?