FMDERIVE for Down Payment Processes

Dear Sirs,

We got to update down payment processes in FM.

We have a derivation step for commitment items derivation from Function Module FMDT_READ_MT_ACCOUNT_COMPANY and "overwrite field not filled" radiobutton selected. This step is making the down payment document creation to change commitment item derived from the Purchase Order. I know I have to select "do not overwrite field not filled" in order to mantain the account assignment from the PO to make a proper down payment updating.

I want to know if I can create a new step with "do not overwrite field not filled" radiobutton selected to use only with down payment processes (value ctg. 61) in its condition, and mantain the existing step for all other values ctg excepting down payments.

Thks.

Gustavo F. Cordeiro