How to add grudges to the existing countries?

CreateGrudge(High Population Density,SouthKorea,CoLCostofLiving,0.1,1,0);

I assumed adding txt files (with above code or similar) in [mod_folder]/data/missions/[country_name]/scripts should let me add new grudges on the existing countries (like vanilla ones or even modded ones). But it seems not working. Any idea on how to do that?