Hi
The "Parent" field will refer to another Task record, where this current task (demand) is located below.
If you want to send a notification to the "manager", I am asking where you find the "Manager" for your demand. If this is the manager of the "Assigned to" user of the Task, you can create a Business Rule to fire on "After UPDATE" of the demand table records, and take the condition "When State changes".
In this case, you can script to fire an event (for triggering the notification), if there is a manager mentioned of the user record of the assigned to user.
current.assigned_to.manager
Use this Sys_id in "Parm1" of the notification and use Parm1 as recipient in the notification.
That way, it should do what you are heading for.
Let me know if that answers your question and mark my answer as correct and helpful.
BR
Dirk
