I got RFE from NSC to ask impact in the field. I got there independent letters from three professors. After i read their CVs, I found one got his PhD degress in the same school where i got my PhD. Another professor got his PhD degree in the same school where i am currently working in. In fact, these two letters are very important to me. I didnot have any connection with them. One happened to cited my paper, another is the editor in chief of my book chapter. I am not sure whether INS will think i have connection with these two professors.If INS does, what i need to do with these two letters? need find other letters? any suggestion will be highly appreciated.Thanks in advance