回複：回複：independent letter

most of the contents are the same. But there are some difference as I know about:
1. Address the point in the notice in each letter and focus on that .
2. You don't need to address the point you have established, i.e. your work is to the national interest,etc.
3. For LC waiver, I can think of these points:
a. your contribution is greater than American with same minimum qualification. So the benefit of issuing you NIW is big than the benefit of hiring someone else (American) to do the job. You have to talk about your outstanding performance in each of your letter.
b. International travel and collaboration is very important for your work. You need to get one letter from international scholar to establish the point that it is a big loss to the national interest ifyou can't benefit from these international collaboration.
c. You can't work in certain area due to the restriction of PR. You can ask someone from governmental agency to say that the job there is mostly limited to PR or citizen. Therefore you lost your chance of working there due to your visa status although you are the best choice for that position.
d. You have been invited to attend certain presentation or talk or meeting but you can't go due to visa. It can also been done by some independent letter from internatioal scholar.
So even you were asked to present the evidence showing LC is not applicable to you, you still have to establish the point that you are better than most of your colleague.
That's my understanding and my lawyer has the simlar opinion.
Wish you good luck.