Jorge,
There are processing options on the Purchase Order Entry program (P4311) for change order processing. Using that setup, you can have a PO return for approvals after a change has been made.
Janet
No, it will not be a new PO. You'll still have the same PO # and type, but there is a change order number (PHCORD) on the PO header (file F4301). It starts at 0 for the original PO and will increase by 1 with every time the PO is changed.