Hello Harvey,
There are several ways to do it.
1. Accept the remaining material of 44,000 kgs on the same line item of the PO & after that transfer it to the other plant.
2. Amend or mark the line item as delivery completed & final invoice & add new line item with the same material code for the remaining quantity with the other plant & storage location details only if the organization structure (pur. org, pur. group & company code) is same for both plants.
3. If the org. structure is different for both the plants then create new PO for the other plant after amrking the first PO as delivery completed & final invoice or amending the quantity.
Hope this helps.
Mangesh S