Protecting individual tags in a tagset

Can anyone suggest a method of protecting tags in a tagset so that accidental deletion of an individual tag is prevented?  

We routinely experience instances where a user might accidentally delete a tag, thus removing the ability for attribute integration with ProjectWise.  In AutoCAD, the attributes are stored in a single entity (block) and it is more obvious when the entire block is accidentally deleted.

Tests so far have suggested that the tags can be moved to a layer & that layer locked, however that prevents any sort of editing in addition to deletion, so this is not a solution.

Thanks in anticipation.