Creating pages under ContentProvider-page causes "entryPoint must NOT have children" exception

Vote:
 

Hello,

we have an ArticleOverviewPage(custom DataPageBase) which has an ArticleOverviewContentProvider: Contentprovider.

This provider creates ArticlePages on the fly(on app-start, matching configured categories) as shortcut to the original ArticlePage. They are listed in CMS and also in frontend.

So far so good. But now the customer wants to create sub-pages under this "blog". But you can't add children to any ContentProvider as documented here. It causes an exception if you try to publish the ArticleOverviewPage(with existing children under it):

Content 19917 given as entryPoint must NOT have children

I guessed to be able to create sub-pages the provider should have the capability "PageFolder". But it didn't work to simply add it to the CapabilitiesString:

private void AddProvider(ContentReference contentLink)
{
	NameValueCollection providerValues = new NameValueCollection
	{
		{ContentProviderElement.EntryPointString, contentLink.ID.ToString()},
		{ContentProviderElement.CapabilitiesString, "Search,Edit,Delete,Move,Wastebasket,MultiLanguage,PageFolder"}
	};

	string providerKey = CreateProviderKeyForContentReference(contentLink);

	ArticleOverviewContentProvider provider = ResolveProviderInstance(providerKey);
	provider.Initialize(provider.Key, providerValues);

	_contentProviderManager.ProviderMap.AddProvider(provider);
}

The error was the same, at _contentProviderManager.ProviderMap.AddProvider(provider) i get:

Content 19917 given as entryPoint must NOT have children

So is it not possible to have children under a ContentProvider, what else can i do? Consider that the blog is here:
https://www.SomeSite/en-us/impact/
and this is the ContentProvider for the articles. Now the customer needs two (static) pages under impact, for example:
https://www.SomeSite/en-us/impact/faq/

Is it possible?

Thanks in advance.

#223747
Edited, Jun 03, 2020 14:50
* You are NOT allowed to include any hyperlinks in the post because your account hasn't associated to your company. User profile should be updated.