No. Derivatives are the investor's spouse and unmarried children under 21 at the relevant time. A daughter over 21 has her own immigration position and cannot be added to her parents' petition.
Derivative status stops at 21
Hypothetical example: a Quispamsis couple's main motive for EB-5 is to live near their daughter, who is 27 and working in the United States on her own employer-sponsored status. Their petition can include the husband as derivative spouse. It cannot include the daughter, because she is over 21, and it cannot include her husband or children.
Her own path to permanent residence, if she wants one, runs through her employer or another basis. Once the parents become permanent residents, family-based sponsorship of an adult child is a separate process with its own waiting periods, and the couple should not assume it will be quick. Any younger children under 21 could be included as derivatives, and the age is protected in certain ways by statute, but each child's date of birth and marital status should be recorded at the outset so the reviewer can advise accurately.