My sister's F4 application was approved 1997 and she is due to go for her interview any day. My question is - I was recently made aware that although at the time the application was made and approved her 2 kids were under 21, but now 12yrs later they are both over 21. What is the next step to take. I was told she has to petition them once she is in US and the priority date will be from 1997. Is that true? How does that work?
Child Status Protection Act http://www.immigration.com/greencard/409/child-status-protection-act-cspa
Contact the consulate for their assessment.