Possibly. She must be unmarried and under 21, but the Child Status Protection Act can freeze her age while the investor petition is pending. Whether it protects her depends on the actual filing and approval dates and visa availability, not on when the money moved.
Her age is measured by the law's clock, not the calendar
The derivative rule sounds simple: spouse and unmarried children under 21 may accompany the investor. Its application is not, because the process can take longer than a child's remaining time under 21. The Child Status Protection Act subtracts the time the investor petition was pending from the child's age at the point a visa becomes available, and requires her to seek residence within a set period afterwards.
Hypothetical example: the daughter is twenty when the investor petition is filed. Whether she still counts as a child when the family completes the residence step depends on how long the petition takes, when a visa number is available for their category, and whether she then acts promptly. Record her birth date, keep her unmarried status in mind, and have counsel run the calculation before deciding to file, because a delay in choosing a project can matter more than any other factor.
No investment agreement, escrow deposit or fee payment stops her age from advancing; only the petition filing starts the protective clock.