Can attachments be added when doing a change on a requisiton that has already been converted to a Pu

 The users have requested that they be able to create an attachment to a requisition change in iProcurement for a requisition that has already been autocreated to a purchase order.  Is this available.  I am not able to see where an attachment can be done on a requisition change after it has already been converted to a PO.

Need help on this right away if possible. 

If not available to create an attachment to a change in iProcurement, is there another process anyone knows about in order to accomplish sending an attachment in with a change request for an exisiting Purchase Order??