How to post RRB CS Cost to FICA instead of FICO

Hi,

I have a query for Consumer funded jobs as a standard process when we do the RRB(resource related billing) billing the values are posted to FICO but my requirement is how we can post it to FICA instead of FICO.

There are some setting we have to do in SD if some one knows will be really helpfull.

Altough I have taken the business partner through FPP1.