Is a Borg rebellion possible? (a metaclass question)

[André]

In my application, I make use of the Borg idiom, invented by Alex
Martelli.

class Borg(object):
    '''Borg Idiom, from the Python Cookbook, 2nd Edition, p:273

    Derive a class form this; all instances of that class will share
the
    same state, provided that they don't override __new__; otherwise,
    remember to use Borg.__new__ within the overriden class.
    '''
    _shared_state = {}
    def __new__(cls, *a, **k):
        obj = object.__new__(cls, *a, **k)
        obj.__dict__ = cls._shared_state
        return obj

----
This has worked very well so far, but is starting to impose some
unwanted constraints on my program design.

What I would like to do is, to put it figuratively, create a Borg
rebellion with various splinter groups.  In concrete Python terms, I
would like to have

class MyClass(Borg, ...):
   ...

seven_of_nine = MyClass(...)  # part of group "BORG"
two_of_nine = MyClass(...)

splinter1 = MyClass(..., group='splinter')
splinter2 = MyClass(..., group='splinter')

and have splinter 1 and splinter2 share the same state, but a
different state than the one shared by members of the BORG collective.

Any suggestions from the metaclass experts?

André