Load one page with parent and child pages

I would recommend not using this in this way.

I use ACF for pretty much everything outside of a basic content area. I’d recommend either using the tabs system or, probably more preferably, the Flexible Content add-on (it used to be an add-on, but is now part of ACF Pro). You can minimize/hide the flexible content sections really easily, and it won’t add to the confusion when editing.

Also, all your child pages will exist separately at their own at their own URL, which could end up giving you way more of a headache.