Ability to add attachments to a requisition which is 'In Progress' approval status

Hi

Does anyone know how a user can add an attachment to a requisition which is currently in progress? So within the approval chain there may be 4 approvers, approver 3 may wish to add an attachment to provide further info to approver 4

Currently, the requisition preparer has to withdraw the requisition by requesting to make a change, add the attachment and then resubmit for approval. This forces the chain of approval to restart

Thanks

Manny