What was the original order quantity ?

During an EDI DESADV message implementation, one of our customer wanted to receive both shipped and backordered (or cancelled) quantities and above all,  the original quantity too. But after line splitting (commitment/shipment), there is no longer original ordered quantity (UORG on the original line has been splitted ). Except in the sales audit order table (taking care about the line number), we loose the  quantity originally ordered by the customer and there is no information on related line (except the order line suffix like 1,001) reminding this line is a splitted line.

How are you usually handling this issue ? Could we imagine to have a new SDSOxx (like SDSO01 to SDSO1x flag) field ?