I have a site for military collectibles. I want to be able to provide hierarchical filtering but am unsure whether to do this by tags or collections because of the nested nature.
There are multiple Products (eg Drum, Acccessories, Helmet) for sale on the site, The main navigation reflects this:
- Drums
- Accessories
- Helmets.
Within drums these are then broken down in 3 collections:
- cavalry
- infantry
- support staff.
Each collection consists of about 7-10 regiments and each regiment has a single drum for sale.
eg Drums>cavalry>Royal Dragoon Guards
My challenge is that many of these 7-10 Regiment have multiple antecedents regiments, that also have a unique drum, but need to be grouped/roll up to hierarchy of the modern regiment that they merged to form.. Eg the Royal Dragoon Guards has both the 4th and the 5th Dragoon Guards as antecedents. They merged and created the Royal Dragoon Guards.
To further clarify: When I show the cavalry collection, it will display 7 -10 regiments (2 of which are antecedents of one of the other 
. I then want to be able to filter by Regeiment. This would then show one or more products depending on how many regiments were selected. Eg if I chose The Royal Dragoon Guards it would show 3 products (the drum for the ROyal Dragoon Guards and the 2 drums of its antecedent regiments). So I would like to be able to filter by this too - ie to then have an option to include antecedents or not.
WHat is the best way to order this? Is it through collections and sub collections? Is it through tags? Or is it through metatags ( I have a shopify2.0 theme)
My challenge is that many of the regiments have been mereged to form a new regiment.