It is possible to update AEM items imported from GatherContent. Follow these steps to update an item:
Navigate to Update section
At this stage you can select any GatherContent project with a mapped template. The items can be also filtered by GatherContent workflow status and Template.
Select items to update
The table will show all items located under the selected node that were previously imported from GatherContent. Select the items to update and click "Update" button. This will launch the confirmation screen.
Click "Confirm" button on the confirmation screen.
View results screen
The update process is similar to the import process. It ends with a results screen where you can view how many items were updated and if there are any errors.