I have an issue and this issue has no due date, but some approval date. What I want to achieve via automation is to send notification to assignee, if there's no sub-task with due date after some time, for example one month, after approval of the parent issue. So that means, one month after issue approval, it should be there at least one sub-task with due date, if no due date notify the assignee of parent issue or if no sub-task the same notification should go to the parent issue assignee. How can I implement this workflow via Automation?