Show different lists of child pages on the same page

Hello,

I have a page that has 4 child pages. On this top page I want to have the 4 child pages as titled sections and beneath each child page title, display a list of links for all (grand)child pages of that section.

So like this:

Child One
-child one child
-child one child
-child one child

Child Two
-child two child
-child two child
-child two child

Child Three
-child three child
-child three child
-child three child

Child Four
-child four child
-child four child
-child four child

I know how to display child pages of the current page but I want to have 4 separate child page lists on the same top level page called by ID of their parents.

Please can anyone advise me on how to achieve this?

Thanks!