'See the docs for xmodule.modulestore.mixed.MixedModuleStore'

def create_child(self, user_id, parent_usage_key, block_type, block_id=None, fields=None, **kwargs):

    with remove_ccx(parent_usage_key) as (parent_usage_key, restore):
        return restore(self._modulestore.create_child(user_id, parent_usage_key, block_type, block_id=block_id, fields=fields, **kwargs))
