How to conditionally print one of several signatures

I'm converting PeopleSoft Crystal checks to BI Publisher and I've read and tested conditional regions but have not seen anything on stacking several signatures in a check form and conditionally printing only one based upon the bank account number.  For instance we might have 4 signatures on a check form and need to suppress or print one if the bank account number is met.  Something like:

if bank_account = '1000' then print Signature1 else

if bank_account = '2000' then print Signature2 else...etc.

I'd like to place a formula on each signature but I don't see a way to do that.  Does it matter if my signature image is