Inclusion of family members follows the official program terms and the derivative rules of the underlying immigrant category, which ordinarily cover a spouse and unmarried children under 21. A child of 20 is at real risk of ageing out unless Child Status Protection Act calculations apply favourably, so confirm the current terms and get that analysis before paying.
A child near 21 is the reason to read the family terms first
The official framework leads to permanent residence through an existing employment-based category, and in those categories derivative status extends to the principal's spouse and unmarried children under 21. Whether the program charges separately for family members and how it handles children who are close to the cutoff are matters the official FAQ addresses and which should be read on the day of application rather than assumed from a summary. Hypothetical example: a Sainte-Brigitte-de-Laval couple with a 20-year-old university student ask whether the child can be included.
The Child Status Protection Act may preserve the child's age based on how long the petition is pending, but it does not cover time waiting for a visa number, and the framework's own processing time cannot be predicted. If the child turns 21 before residence is acquired and the calculation does not protect them, they would need their own route. A child who marries loses derivative eligibility.