5. In POS you should perform validation in the project PRICE method GetPrice() (this method you returns the value of the article), what you should do is go to search for that data in the new in the BD with SQL statements on the basis of the item and module which in this case would be sales and already with this simply valid and assigning the new price if you pass your value.

6. Compilas the DLL and the remplazas and should in theory funcionarte.