Thx for all your replies.
I'm not sure what multi-level means. Like upgrades? Maybe I forgot to paste that in from the question. We'll probably get to the de-building-ification of workshops before we do anything like upgrades, which'll accomplish something similar through furniture.
I mean by that to be able to mod in a workship with a multi-level-structure similar to the metalsmith forge, where you first select a material (Iron, Steel, ...), then a category (weapon, armour, ...) and finally a product (short sword, axe, ...)
Let's say you want to mod in additional types of steel and want to assign all steel types to a custom created seperate Steel Forge. As far as I have understood you currently have to make tons of unique reactions, one for each possible product and finally get one huge list in the custom workshop with "Make Steel Axe/Helmet/Large Serrated Disc/etc./Make Nickel Steel Axe/Helmet/Large Serrated Disc/etc./Make Damascus Steel Axe/Helmet/Large Serrated Disc/etc. ... With multi-level I mean you can create a custom Steel forge, and as with the standard forge you first select material (Steel, Nickel Steel, Damascus Steel), then define the categories like weaponry etc and finally all the possible products are automatically assigned to those categories according to the Material tokens (ITEM_HARD, ITEM_WEAPON, etc.), you assigned to the specific materials.