My wife was brought here on a K-1 Visa but we could not afford to bring her children with her originally. Now we have been married 3 years , has her permanent 10 year Green Card, she has a very good job and we want to bring her two boys (11 & 9) . I heard of a process called something like "follow to immigrate" for young children of K-1 beneficiaries. How does that work and what forms/documents do we need to process, and how long does it take?