Magento ::: auto display products from child categories on top (parent) category without 'is anchor'

All my products are assigned to sub categories - I want All products to also display on the parent categories without explicitly assi开发者_如何学编程gning them.

is anchor is not good for me, because it does not use the seo-friendly urls for the sub categories, and this is an important requirement for me.

Is there another way I can achieve this, even with an extension?

"is anchor" is fine as long as you have the canonical urls set correctly. We use Mageworx SEO Suite to control this and it works well