BPM for PO Suggestions

Let me preface with, I'm a BPM newbie. I want to write a BPM that fires when a PO Suggestion is generated in a Purchase Order. I want to take the POSugDtl.SugNum field and write it to the POHeader.ShortChar01 field of the PO that is generated. From my Trace Log I think I need to use the POSugg BO and the Generate method. But I'm stuck at the 4GL needed for the Action. It seems like with this method I would have multiple temporary tables- ttPOSugDtl (for the deleted suggestion) and ttPOHeader, ttPODetail and ttPORel (for the PO being added) but I'm not sure...

Any one have any idea if this can be done? Any if so, what my 4GL should look like?