Sales Orders lines deleted by script screws up Sales Order History

SOLVED

With Sales Order history enabled, lines that are deleted by an event script (Pre-Totals) are not reflected as CancelledLine="Y" in SO History. Thus, there is no way to differentiate deleted lines from lines that remain in the order.  This results in overstated and unusable SO Quote/History reports. Lines deleted in Sales Order data entry are reflected as CancelledLine="Y" and can be filtered.

Any ideas how to identify deleted items? I don't think there is because all other fields are identical (other than the key fields).

Any ideas how to make scripting work as the user interface does?