Yes, you can backflush an item with an estimated quantity = 0.00 if you haven't already backflushed the order. For example, you had an order with one component, you reported the quantity at the operation or order level and ran the backflush. Now you realize you need another component added. In this example, the order has already been backflushed, so if you were to add a second component, run backflushing, nothing would happen.
Backflushing is based on the 'quantity to backflush' in report operations or report orders complete. When the quantity is backflushed....