I agree with _Maxxx_,as a user after encoding a objects/records(rooms,classes,locations) and there is something he miss out and decided to cancel everything he puts up, then, there should be a warning message saying all the encoded data will be erased/not saved.. I think its only a matter of proper error message to the user, and not to complicate things in saving the current session/child which may lead to data redundancy and confusions. A linear transaction is what I'm suggesting.