SUS PO Confirmation not reaching ECC PO

Dear Experts,

I created a PO it reached the SUS Vendor. I changed the Quantity of PO and sent it to the Sender of the PO. But the confirmatoins tab is not updated with updated quantity, The updated quatity is saved in SUS po but it is not reaching the R/3 PO.

The requirement is to get the updated quantity and remaining quantity of PO in Confirmation tab.  eg: if ordered PO quaitity is 5. Vendor responding with 2 and reamaining 3 has to to be shown to Confirmations tab. Presently the Updated and reamining quantities are not shown.

Kindly guide me how to proceed.

Thanks in advance

Arun.K.P