How to populate a parent page with its child subpages and associated templates

You should look at archives.php. What you trying to do is create a custom post type loop (“pages) in different sections of your template. You have to filter by category, taxonomy, or tags to set up your different groupings.

http://www.wpbeginner.com/wp-tutorials/how-to-create-a-custom-post-types-archive-page-in-wordpress/

https://stackoverflow.com/questions/30883218/custom-post-type-wordpress-query-by-category

I think this is what I mean: List all posts in custom post type by taxonomy