Expediting - How to update PO and Sales order Delivery Dates?

When a supplier changes a delivery date for items on PO, how do you update the PO and related Sales Order delivery dates? Seems like there should be a function like a backorder release that would run against purchase orders and sales orders with backorders. If there was some sort of tie between a PO and sales orders, when receipt of the product from the supplier is delayed, you could automatically update all related POs and Sales Orders and even notify the user that entered the sales order and the customer of the change to the delivery time.