the post types of my instance

@saunders I'm uploading two screenshots:

1) child-post-settings: the default configuration for this type of posts.
2) child-post-info: the information included into the demo contents, explaining what child posts are meant to be. Basically setting Use Parent ID to Option or Required let you associate posts of this type to any other post by ID, from the edition form.

You can go to the demo site to see how a child post is set up. More specifically:
http://demo2.b2evolution.net/stable/index.php/a/child-post-example

(and log into the backoffice to see details)

@fplanque I understand how to technically manage child posts. But the concept of child posts remains hidden to me - except the possibility to use custom fields defined in referred ID.

That would be helpful to know:

1 When (besides grabbing custom fields of the parent post) does it make sense to use Child Post? Whats the value proposition?
2 Does a child post with regard to SEO keep the same performance as normal posts?
3 Is there an information on the referred ID Post, that one or more Child Posts exist?
4 Do I have to convert a Child Post in a Post in case I want to delete the referred Post?
5_ Is there a way to visualize the hierarchy or do I have to check the entry format in the backend?

1_ When (besides grabbing custom fields of the parent post) does it make sense to use Child Post? Whats the value proposition?

They are only designed for grabbing parent values.

2_ Does a child post with regard to SEO keep the same performance as normal posts?

There is no difference.

3_ Is there an information on the referred ID Post, that one or more Child Posts exist?

I think we haven't developed that; but we could if it we had a use case for it.

4_ Do I have to convert a Child Post in a Post in case I want to delete the referred Post?

No. It will just be a "broken link".

5_ Is there a way to visualize the hierarchy or do I have to check the entry format in the backend?

No, there is no way to visualize the hierachy. It's not designed to build hierarchies.