thevittfile

The plugin looks up the sub-attributes in your product, then for each value it looks up its parent and adds the parent attribute and the parent value in the product. 
When using a filter with the main attribute on the store page, all the products that have that main attribute are returned, which are the same products that contain the associated sub-attributes.
Important: 
You can’t create multiple hierarchy levels, just one. 
Two diferent attributes cannot contain the same sub-attribute.
<h3>Documentation</h3>
<a href="https://github.com/vittfiles/vitt-attribute-hierarchy" rel="nofollow ugc">vitt attribute hierarcht for woocommerce</a>

Vitt Attribute Hierarchy for WooCommerce

This plugin works simulating a hierarchy for attributes and subattributes.

liveseopro

Custom Image Attributes is a lightweight WordPress plugin which allows you to add custom attributes to images on your website. You can add attributes to single images or all images.
You can use this plugin to add attributes to images as required by some other plugins, such as for lightbox, analytics and seo purposes. Add any attribute you like. Examples include;
data-lightbox=image-ad1 
title=demo 
alt=demo 
fetchpriority=high 
click-id=promo1 
or id, style, class, data, toggle & more
Free Features 
Add attributes to all images on your WordPress website. 
Add attributes to single images 
Remove attributes 
Disable native lazy loading for an individual image
Get Support 
Get limited support for this free plugin via the support tab.

Custom Image Attributes

Add custom image attributes to any image. Great for adding attributes to images for lightboxes, SEO, analytics & more.

Vitt Attribute Hierarchy for WooCommerce vs Custom Image Attributes