Possibly. Unmarried children under twenty-one are derivatives, and the Child Status Protection Act can subtract the time the investor petition was pending from his age when a visa becomes available. Whether that keeps him under twenty-one depends on the actual dates.
Run the age calculation on real dates, not hopes
Hypothetical example: a Mission couple file an EB-5 investor petition when their son is nineteen. If the petition takes two years to approve and a visa is available immediately, his age for eligibility purposes is his actual age at that point minus the two years the petition was pending, which keeps him under twenty-one, provided he seeks to acquire the visa within the period the law allows. If a visa is not immediately available after approval, the years of waiting are not subtracted, and he may age out.
The calculation is mechanical but unforgiving, so it should be run before filing rather than after. If the result is close, the family may wish to file sooner, consider whether he has a route of his own, or plan for him to remain in Canada as an adult. Derivatives cannot work until residence is granted.
Hypothetical example: An investor has a nineteen-year-old stepchild and plans to file after a delayed property sale. The first review should confirm the legal relationship, the child's age and the timing of every filing and visa-availability event. Birth, marriage, adoption and custody records settle family eligibility; petition receipts and visa records matter for any age-protection calculation.
Conditional residence does not remove the need to preserve documentary proof for each derivative. If the child may age out, assess that risk before deciding when to file or whether the investment route fits the family's timeline.