Relative dates for subtasks backward from parent task due date

Hi -

I’d like to create a Task Template with relative dates for subtasks that change based on the parent task due date.

For example, subtask 1 is due 15 business days prior to the task due date and subtask 2 is due 13 days prior to the task due date. When the task due date is created or changed, those subtask due dates are then created or changed.

I’ve looked into rules and the “Set a relative due date” feature in the task template - but that only counts moving forward from the day the task is created, not backward from the due date.

Asana AI tells me this is not something Asana can do - has anyone else requested a similar feature?