Per Shipping Executon Development , the following can be done -
Utilize the 'UnderShip tolerance' functionality to achieve the desired functionality .
Following example will clarify the way profiles 'OM: Under Shipment Tolerance' and 'OM : Over Shipment Tolerance' work.
Ordered quantity on line is : 50
OM: Undershipment Tolerance is : 10%
OM: Overshipment Tolerance is : 10%
So,There is a tolerance for 5 units( 10 % of 50)
Case 1) When a quantity of 53 is shipped, there will not be any error message.
Case 2) When a quantity of 57 is shipped, there will be an error message saying overshipment tolerance is exceeded
Case 3) When a quantity of 47 is shipped, there will not be any error message and the line will not get split.
Case 4) When a quantity of 43 is shipped, there will not be any error message, but the line will be split into 2( 43 and 7 (backordered))
There is an enhancement logged as below to show warning message
ER # 5349942 Abstract: OM: UNDERSHIPMENT TOLERANCE SHOULD PROVIDE WARNING MESSAGE
However this has certain limitations as follows:
a) Tolerance is applicable for a line. So, if a user has 2 lines in an order and if customer shipped only one of them the other line will still be open
b) The user has to run Interface Trip Stop immediately after shipment so that the remaining quantity is cancelled.
Otherwise, there is no other way to cancel/reject a backorder.