We have a system where we need to limit the amount of asset going into an address, based on a calculation done outside out multichain. Could we use waleltnotify to see the transaction, but if the calculation decided it should not be confirmed, then the send and receive address could be revoked so the transation would not be confirmed on chain - if that is possible, what happens to the asset that has been sent by someone else..does it go back to them, or could we simply write a command to send it back?