I’ve done something similar using Data Directives. I added an In-Transaction directive on the OrderDtl table that basically looked at the order to see if the UnitPrice = 0. If the UnitPrice = 0 then a warning message pops up notifying the user that the unit price is 0.
It may seem a little messy, but basically if the results of the query are UnitPrice = 0 (AND the PartNum is not one of the special parts) then the warning message will popup. -This will happen in OrderEntry, Customer Shipment Entry, anywhere the OrderDtl table is being used pretty much…
Now I know this isn’t exactly what you want/need but I’m hoping this can point you to the right direction, or maybe just give you an idea of what can be done. I’m pretty new to BPMs in general so I may not be the correct person to reply to this, but I’ll help any way I can.
EDIT - So looking at the way you want yours to be, I think one way to do it would be something like -