My friend's application for an immigration visa was approved some time
ago. She will come to work in a flower farm as a gardener. She may
have to wait outside of the United States for up to two year to
enter. When applying, her teenager daughter was her dependent. It is
said that after the age of 21, dependents have to apply for
themselves They will no longer be in the same category with kids
younger than 21.

My question is: if my friend's daughter is over 21 at the time when
they are allowed to come, can she still come with her mom? In other
words, will her dependent's status become out of date? If this girl
gets married and has kids, what would happen?

Thanks for your expertise on this matter.
Fulio Pen