add_filter('register_post_type_args',	array($this, 'method__modify_post_args'), 150, 2);

// method 2 (seems useless):  child posts go to 404
	function method__modify_post_args($args,$p){

		// example of registered output: $args  https://pastebin.com/raw/pNA5vjNn
		if($p=='post'){
			$args['hierarchical']=true;
			// 'query_var'  doesnt change anything
			// $args['rewrite']=true;    // causes fatal error, because rewriting yet not initialized
			$args['labels']["name"]="Posts";
			$args['labels']["singular_name"]="Post";
			//$args['label']="Posts";     //doesnt change anything..   more labels in: wp-includes/post.php
		}
		// example of set_args func: https://pastebin.com/raw/VxZAJcqC
		return $args;
	}