Issue: No Book TOC Nesting

Can you help with the table of contents?
I can not display article of the children-books in the table of contents of the father-book: I created a father-book to which I connected three children-books each containing few articles, but the table of contents of the father-book there are only children-books and not the articles.
How do I order to display the pages of children-books?

I see this:
1 Cap1
2 cap2
3 cap3

I want to see this (as the index of the VaultWiki Manual):
1 Cap1
. 1.1 par1.1
. 1.2 par1.2
2 cap2
. 2.1 par2.1
. 2.2 par2.2
. 2.3 par2.3
3 cap3
. 3.1 par3.1
. 3.2 par3.2
. 3.3 par3.3
. 3.4 par3.4