Modding

Question: Does anyone know if it's possible to modify hero specializations that grant buffs to creatures? For example, could I make it so that Dugald gives a buff not only to archers and their upgraded versions but also to another creature specified by its ID? Is this information stored in the game files, or is it "hardcoded"? How were hero specializations that buff creatures implemented in the NHF mod, through scripts? I would be grateful for any information.