Update EKES Table fields using BAPI - Urgent?

HI ,

I am using the ME22N transaction to change the Purchase order. I need to update some of the fields such as confirmation category, Delivery Date, Quantity, Sequential number and the Reduced Quantity field.

Can anyone tell me how to update the EKES table? Which BAPI or user exit or BADI to use?

I have a BAPI named BAPI_PO_CHANGE but i cannot use it because the Reduced Quantity field DABMG in the EKES table is not there. I know its calculated but how can i do that ?

Please let me know your comments.

Thanks.

Varun.