Help to create a custom Attribute filter

Hi! I’m trying to find a way to create a custom filter that relates an attribute to an attribute WITHOUT changing the attribute structure itself.

For example, if I have attribute “size” with the values 44, 42, L, I’d like to link them all together in the back end to the attribute “size” Large.

More information: I’ve just built my ecommerce wordpress website with woocommerce plugin, using WP-Lister for eBay Import from eBay to WooCommerce plugin to retrieve my ebay listings as my products.

My ebay listings have numerous size types which are imported as attributes. Like the example above, size Large could also be attribute L, 42, 42L, 44, Large, etc.

Also, different ebay items are using different attribute categories, so some items use attribute “size”, others “Men’s size”, and then within those attributes are also the 42, 44, Large, etc.

I am looking for a way to link all of these different attributes so that if a customer would like to search for all items in “size” large, all of the attributes shown above would appear.

I’ll be refreshing my inventory at least weekly and would not want to do so many updates, so while I could change the attributes of all of these items to Large or create a new attribute called Large and then update all products that are 42, 44, etc to that attribute I’d have to do that every week.

Any help would be appreciated! Thanks!