FMS Query?

Hi Experts,

i have createrd a UDF on the Item master data and i have also ceated 2UDF's on the delivery note.

I have created a FMS with a query that updates the UDF(Opening Readings) with the value from Item Master data.

Now for me to achieve the second UDF on Delivery i want a query that will subtract the Opening readings UDF from Quantity entered.

I want the subtraction to happen immediately the quantity is changed.

Attached is the images for your assistance

Urgent help will be appreciated

Regards

Justice