Business area field while uploading electronic bank statement

Hi

I am uploading the EBS. The statement is in MT940 format. However my problem is we have business area as mandatory entry. We take Fin statements BA wise.

At the time of upload I am nowhere giving the BA. So I am unable to post the statement automatically.

How do I make the BA to get determined.

Is substitution a good option as my bank accounts are BA specific.

regards

sameer