Not sure if this feature is not available yet, or if I am missing something but, does anyone know if the below is possible to achieve:
When using @Everyone on this item tag in the comment section of an item, I want everyone who is assigned to the parent item and subitems to receive the notifications.
When using @Everyone on this item tag in the comment section of a subitem, I want only people assigned to that subitem to receive the notification.
At the moment, when tagging @everyone in the updates section of an item or subitem, the only people who will be notified are those who are subscribed to that item or subitem. It will not notify the subitems of a parent item or the parent item of a subitem.
However, this sounds like a really interesting capability to add, so I would highly encourage you to actually post this as an offical feature request here!: Feature Feedback
This way, other members of the community can also vote for it and add why they would like to see it added. Our Product Team takes user feedback very seriously! In fact, many of our features began as user requests.