Forcing a specialty on native settlements.

I would like to know if anyone can tell me if it is possible to explicitly, in the editor or in code, tell a native settlement EXACTLY what specialty I want it to have. e.g. Expert Farmer or Expert Cotton Planter. I have tried to place native settlements and replace them over and over to make them have what I want, but when I would save the game from the WB and reload it as a custom scenario, the freaking specialties they had reset to their own liking!!! I am feeling let down, but I am confident someone here can lend me a hand in pointing out how I can alter this. If I have to modify code, go ahead and tell me where to modify, if you know where, and I have skill in coding, so it will be fine. Thank you in advance.