This extension may be useful: https://www.opencart.com/index.php?rout ... n_id=17351
The most generated errors being found on Opencart forum originates from contributed programming.
Just create a link where you want it that includes /index.php?route=product/search&tag=children after your domain url. I do this on several of my stores to link to products with different tags.
Running Opencart v2.2 with multi-stores from http://www.labeshops.com which has links to all my stores.