My parent stayed here illegally for about 1 year and now they are in China. I just got my citizen and hope to apply GC for them. I heard there is a 10 years bar, the question is they didn't return their I-94 when they left and their passports are totally new, the numbers are totally different to the old ones. My questions are how can INS know how long they had been here? Do we face a big trouble? any way to avoid this? appreciated for your advice.