Some changes it seems you just can’t do via subclassing for reasons unexposed to us. Take for example the inventory on an item such as the Fabricator, you can’t go into the inventory on that and change recipes to point at a new item unless you copy the main StorageBox_Fabricator blueprint. The rest of the blueprints in the reference chain like the EngramEntry and the PrimalItem are all fine as a subclassed item though.