A date in an item from a subitem

Hi i have parent items and subitems. In subitems i have actions that took place. Each subitem represents an action that took place for the paren (a service request).
Each action or subitem has an action date. And there are many actions. I would like to have in the parent item the date that the first action took place. So at the moment I have an automation that says when status of the subitem is “done” set date in parent item to today. But that requires that the user updates on realtime the system. Is there a way to update the parent column (first action date) with the specific action date of the subitem.
Thank you!