How to realise an unconventional permalink structure

For a client’s website, I need to build a rather unconventional permalink structure. Multiple child pages, as well as a custom post type, with all its post archive pages and single posts, need to exist below a parent page. Like so:

– Parent Page (mydomain.com/parent)
— Child Page 1 (mydomain.com/parent/child-1)
— Child Page 2 (mydomain.com/parent/child-2)
— Child Page 3 (mydomain.com/parent/child-3)
— Custom Post Type (mydomain.com/parent/custom-post-type)
— Custom Post Type Entry 1 (mydomain.com/parent/custom-post-type/entry-1)
— Custom Post Type Entry 2 (mydomain.com/parent/custom-post-type/entry-2)
— Custom Post Type Entry 3 (mydomain.com/parent/custom-post-type/entry-3)

I’ve had a look at the URL Builder plugin by CalderaWP (https://calderawp.com/downloads/caldera-url-builder/). But their support told me, that unfortunately this type of URL structure is not supported by the plugin.

Any ideas, how this could be achieved in WordPress?

Thanks!