I filled online, click continue and get a pfd file. I saved it as file1. Afterwards I read the instruction that you can not leave anything blank, I filled another one online, just to add NA to some of the questions, get another file and saved it as file2. After reading posts here, I found NA is not necessary. So I sent to my parents file1. But I read the comments here, seems I must to VO the last file generated when being interviewed. Is that true?