the ages of children are not above 21 years:
1. when should we file appropriate form to avoid that? The form is I-824?
2. I got that Form 824 should be filed within one year after Form I-140 is approved?
3. for my understanding, when or after I-140 is approved, and visa number is available(that is, when filing Form 485) when child is younger than 21 years old, the child's GC will be protected?