Thanks for the suggestion. Is it possible to play with the brainwallet on the testnet? I have taken a look on it before. The issue is that the functionality of brainwallet is very simple and it seems not support sendtomany() now. Sure I can first send it to standard wallet and then create another transaction, but it takes an hour and increase the error.
The standard client have commands for all type of transactions, that is why I want to know whether the scheme described works or not?
Sendtomany? Like send amounts to 2 different people from the same private key? If you use the + button next to the destination address, you can add multiple destination addresses. That's why I was saying you should probably specify what change address to use by adding it as another destination address.