回複：Too long. Only stress your own

That was why that the officer only read this letter (My parents said that the officer read the whole letter). And the officer only asked two wuestions (1. Why do you want to go to the USA? 2. Where does your daughter live?), then issued them the visa. I guess the best way is to write whatever you think is convincing and touching and it does not matter if your letter is longer or shorter. If you do not feel comfortable with what your talking on the letter, just do not write it down.