Under the current official terms, a spouse and unmarried children under twenty-one may be included in the initial application, with a separate processing fee and gift for each. An adult son qualifies only if he is still unmarried and under twenty-one. Re-verify the family terms and amounts before paying.
Family terms belong to the program, not to analogy
The current official framework permits a spouse and unmarried children under twenty-one to be included in the initial application. Each included family member is currently subject to a separate processing fee and gift, and a successful family member receives the privileges of lawful permanent residence, including employment authorization. The builder should read the official family terms again immediately before applying because the amounts and procedures can change.
If the son is married or has reached twenty-one, his own plan is a separate question: a student category through a certified school, or his own employment-based route if he has a listed profession and Canadian citizenship. The family should confirm every person's eligibility and required payment before anyone gives notice or leaves school.