No. Review each person’s circumstances and the applicable rules individually.
Keep the household assessment separate
Consider visa availability and any CSPA issue using actual dates. A contribution or filing does not automatically freeze a child’s age. Eligible derivatives are a spouse or unmarried child under 21, subject to any applicable CSPA calculation; a family member does not need another principal investment merely to accompany.
Raise any child approaching twenty-one with counsel at the first meeting, because the analysis of how age is calculated in these cases is technical, depends on the specific filing history, and can influence how quickly the family wants to move. Ask counsel how a child's age would be assessed on the route contemplated, since age protection depends on the facts rather than on a fixed rule, and preserve documents supporting each person's relationship and birth details. Keep the invested capital ring-fenced from money the family needs for school fees, housing, and ordinary costs, because a delayed exit is a financial event rather than an immigration one and does not by itself affect a derivative case.