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?

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"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