'Only sync StudentModuleHistoryExtended to StudentModuleHistoryExtendedRouter.DATABASE_Name'

def allow_migrate(self, db, app_label, model_name=None, **hints):

    if (model_name is not None):
        model = hints.get('model')
        if ((model is not None) and self._is_csmh(model)):
            return (db == self.DATABASE_NAME)
    if (db == self.DATABASE_NAME):
        return False
    return None
