No. Derivatives are limited to the investor's spouse and unmarried children under 21. An adult married daughter would need her own immigration basis, which could include her own EB-5 investment.
Adult children are separate applicants
Hypothetical example: a Frontenac Islands landowner intends to invest so that his daughter, 25, and her two young children can live near him in the United States. The rule does not reach that far. His conditional residence extends to his spouse and to unmarried children under 21 at the relevant date, with the Child Status Protection Act freezing a child's age at the filing of Form I-526 or I-526E while it is pending.
A married daughter of 25 is outside that in two ways. She could invest herself if she has qualifying capital of her own, or could receive a documented gift from her father, in which case the file must trace his funds as the source of hers. Alternatively, once he holds permanent residence he could sponsor her in a family preference category, though those categories carry long waits and marriage affects eligibility until he becomes a citizen.
The plan should be built on what the rules give him, not on what the family hopes. Hypothetical example: A Frontenac Islands wildlife-photography business owner has an unmarried son who is twenty and plans to file shortly before his twenty-first birthday. The first review should record the son’s age, marital status, and expected timing with identity documents.
The petition filing date, visa-availability date, petition processing time, and the child’s timely steps to seek permanent residence all affect the Child Status Protection Act analysis; marriage independently ends derivative-child eligibility. The family should not assume a later family preference petition will preserve the same timetable.