PO to delivery copy control

Dear All,

I have this situation where I create a delivery for a Purchase order STO process.

Now my requirement is that I want the exact value of Item number in Purchase order to also be in the Delivery.

Example

in PO i have item

Item Number      Item

010                    ABC

020                    XYZ

030                    MNO

So now when i create a delivery without item number 020 because of E.g Differnt delivery date.Then i want the new delivery to have the following

Item Number      Item

010                      ABC

030                     MNO

Maybe copy control might help,But can anyone help me to actually make the code changes ,or is there any other way.

thanks