回复：my daughter was my F1 dependent at School A. but

when I transered from School A to School B in 10/2005, School B forgot including my daughter in Form I-120. Until half year later(5/2006), we found this problem, and School B issued me new I-20 with my daughter as my dependent.

That means that my daughter was out of status from 1/2005 to 5/2006?
-No more. Because your kid has re-instated her F2 status after 5/2006, her record of out of status is considered removed and it will not affect her anything in the future.