Showing blog posts in parent category

I have a folder called /blog/ and a few folders below it (would be blog categories). If I write a new post in one of those inner categories they don't show up in the upper category feed/page.

Do you know how I can change that?

Thanks

ps. I rather not add the blog posts to both the upper category and lower category if possible.

 

Ignore the post above. I had to add /category/ to the URL which I guess Wordpress adds by itself

 

Do you have a category plugin ?