It's just their wish, in order words they want to be rich as possible, not really to ensure generational wealth.

In reality, there's a proverb "shirtsleeves to shirtsleeves in three generations", they don't need to think about the fourth kids, what they should focus are the third kids where they don't have any control since they're already dead.

Anyway, before they think about generational wealth, better they need to focus to control their spending first those young generation like to wasting money for unnecessary thing.