How to handle non-stereotyped metatypes in the new model version of MDG?

[Paolo F Cantoni]

In our hand-crafted MDG technology, every metatype notionally had to have a stereotype.  However, our repository still has unstereotyped items in it.  This is, principally, because we can't stop the "default" Sparx set of items from listing on our toolboxes.  (If that's changed, please let me know).

Is there any way to create a "stereotype" for an unstereotyped metatype?  (I know it sounds self-contradictory!).  (For example, an unstereotyped Boundary element)
We want to convert our handcrafted and metadata supported MDG to a full model-based MDG.

Is it better to require EVERY metatype to have a stereotype and have an implied default for any unstereotyped item we find?  Our automation would then automatically convert the unstereotyped item top the default stereotype.

TIA,
Paolo