Updating sales order line UDFs

Hello experts,

I have to update two UDFs on sales order row when it's partial delivered or closed.

It's works fine only if the order status is open.

If the order status is closed, the DI API returns 0 (no errors) but the two UDF are not modified.

Is it the expected behavior ?

How can I update a sales order line UDFs of closed sales order ?

Can someone help me to achieve it ?

Thanks in advance for your time.

Best regards

Andrea