Flat pages with selected default site

flatpages.py

#admin.py
from django.contrib.sites.models import Site


class ExtendedFlatPageAdmin(FlatPageAdmin):        
    fieldsets = (
        (None, {'fields': ('url', 'title', 'content', 'sites', )}),
    )
    
    def formfield_for_manytomany(self, db_field, request=None, **kwargs):
        if db_field.name == "sites":
            kwargs["initial"] = [Site.objects.get_current()]
        return super(FlatPageAdmin, self).formfield_for_foreignkey(db_field, request, **kwargs)


admin.site.unregister(FlatPage)
admin.site.register(FlatPage, ExtendedFlatPageAdmin)