Locking a form with multiple digital signatures

I am having difficulties locking a form that has multiple digital signatures.  This particular form has signature fields for the requisitioner as well as 3 approvers.  If I have signatures in all 4 fields the option to lock the document appears as the last approver signs it.  My problem is depending on who the requisitioner is they may not need approval from 3 people.  Maybe only 1 or two.  The lock option only appears after all fields are signed.  I was hoping it was just tied to the last signature field, but even if I skip down to the last signature field it doesn't give me the option to lock.  Its only after I go back and fill in the other signatures that it finally gives me the option to lock.   Is there away around this somehow?