I'm not quite following you. Could you explain what you mean by cascade down to the children?
I'm sorry, I still don't follow. What do you mean by "a root page where I add a no index (or something)"? When you say "cascade" I'm thinking CSS (cascading style sheet) but I guess you don't mean this in your post.
If I understand you correctly you mean that settings for a parent page to propagate to child pages. In this case this is not possible with one exception - you could create a page template from an external master page and set all the needed <head> tags in the master page. Then all pages that need a specific behaviour could use this template based on the master page.
Ok, we take into consideration your suggestion in this case. I will communicate your suggestion to our designers team to see if the implementation of such feature would fit our requirements.