Presently the Mpf_Figure class does not support mpl subfigure plots. Subfigures allow encapsulation of a group of subcharts into one figure that can then be embedded easily in the overall figure

Adding the following function to Mpf_Figure class will add in subfigures

 def add_subfigure(self,*args,**kwargs):
 if 'style' in kwargs or not hasattr(self,'mpfstyle'):
 style = _check_for_and_apply_style(kwargs)
 else:
 style = _check_for_and_apply_style(dict(style=self.mpfstyle))
 sf = mplfigure.Figure.add_subfigure(self, *args, **kwargs)
 sf.mpfstyle = style
 self.subfigs += [sf]
 return sf

Current Alternative solution / workaround is to sub-class Mpf_Figure and add this in. It would be preferable not to have to do this as SubFigure are part of the mpl and should be supported in mpf