PO:Can only the 1st approver be required to enter his id/password?

Summary:

Client requirement is for all the PO to be routed 1st to the buyer who will enter the id/password and then it will travel the approval path. This requirement coming from client is a FDA requirement.

We can setup the PO approval path in a way that the 1st approver is the buyer who will give his id/password. On the BPM side we have Signature Policy to 'Password Required'.

But this has a drawback that all the approvers in the PO approval path have to enter their id/password. We want only the buyer (1st approver in the path) to enter id/password & then remaining folks will just hit Approve.