Overwritting COPA values once derived by substitution rule

Hi,

We have a substitution rule enabled to derived COPA segment to get the IC customer in the Invoice of the saler order.

However, for certain customer, we need to blank out or replace the customer with something else as the what the system derives is not requiered for reporting purpose.

We create a KEDR rule to derive the customer. However, manually when I check Pseg, it picks the required customer but when the invoice is created by system, it is not picking the customer from the KEDR rule. Substitution rule is overwritting the KEDR rule.

Can anyone tell me how to make sure that KEDR rule is applies after the substitution rule to derive the PSEG which we require.

Thanks