My sister in law turned 21 last summer. Before which, her application for a green card based on my mother-in-law's residency status was received and approved, but no visa numbers were available. Now, my brother-in-law (who is 20 years old) just received notice of a visa appoinntment, but his sister did not. We assumed CSPA meant they would subtract the time that a visa number was unavailable from her age. Were we supposed to apply for something or did we misunderstand the Act?