PO release

Dear Friends

i have a scenario where the payment terms in the PO have to be changed by purchase from that maintained in the master. currently the PO has a 2 level release strategy. is it possible to configure a 3 level release strategy that will trigger only when the payment terms are changed in any PO. i fail to visualize how for any given PO a 2 level strategy exists for normal conditions and a 3 level for any change in PO. please advice

regards