mandy_lee,
問題係你家姐/妹apply 你.. 佢收到application 收據嘅date or approval date??
如果只係application date, 唔係 approval date, even 21歲都冇用.. ask your sister to read the letter again.. check that is it a notification of received application or an approval letter for your application?
received application notification 係冇法律效力.
If the law didn't change, it is 21 years old. I was 21 years and 1 month old when my family received the letter to ask my family to have body check, criminal record, etc. But since I was over 21, my name was not on the letter lor. After my mom landed in the U.S., she applied for me again, but it took a long time...9 years ah...