Tags within tags?

So, I have been trying to implement a new "machine" in for my mod that will turn ANY kind of wooden block into sawdust and so I created a new tag and tried listing various other wooden block tags such as "minecraft:planks" and "minecraft:wooden_fences" under said tag but when I go to make the sawdust in-game it doesn't seem to work.

I have done a fair bit of research online but still cannot figure it out, am I missing something or can you not tag other tags?