Do not assume so. The official FAQ sets separate family terms that must be checked for the actual applicants. Current official terms add a US$15,000 processing fee and US$1,000,000 gift for each eligible joining spouse or unmarried child under 21, including corporate cases; confirm individual eligibility and the operative instructions.
Build a person-by-person record
Identify relationships, ages and intended inclusion. Have eligibility, current financial terms and any age-related issues reviewed individually rather than treating the principal’s plan as a household approval.
Other routes have well-settled family provisions, and it is tempting to reason by analogy: a spouse and unmarried children under twenty-one as derivatives, work authorization in some categories and not others, study permitted for dependants. The 19-year-old is within the unmarried-under-21 range but must also satisfy the adopted-child relationship requirements to qualify; being an adult in everyday language is irrelevant. Review each teenager’s date of birth, unmarried status and any applicable age-protection rules with counsel before comparing waiting with a current application. Record birth dates, marital status, passports, relationship documents, admissibility issues, and who genuinely plans to immigrate.