No. The spouse and unmarried children under 21 are derivatives of the investor's petition and receive conditional residence on the same basis. Each derivative completes their own residence application and is generally included in the investor's Form I-829, although separate filing can be required in some changed family circumstances.
One petition, separate applications for each person
The investor petition is filed by one person, and only that person must satisfy the capital, source-of-funds and engagement requirements. The spouse and each unmarried child under 21 are included as derivatives, which means they obtain conditional permanent residence because of their relationship to the investor rather than on their own qualifications. In practice each family member completes their own immigrant visa application or adjustment application, attends their own medical examination and is assessed separately for admissibility.
When the time comes to remove conditions, the investor files Form I-829 and the derivatives are generally included on it, though a spouse or child may need to file separately if the family situation has changed. Once residence is granted, the spouse may work and study without restriction. If the gift came from the spouse's parent, that does not change the analysis; the money became the couple's, and the investor named on the petition is the one who invested it.
The children's ages are measured under the Child Status Protection Act.