Currently, I am filing for OR category in VSC. I already had two independent big shots letters. I also asked two of my previous colleagues who are not from my home country and one is a professor in a top ranked international university and the other is working in a Big British company. I also consider these two as indepdent letters. All together I had 13 letters, other 9 are all from my previous boss, current boss and previous known professors. Do I need more independent letters?