Re-using parts of a one time pad to encrypt a new one?
Let me get this straight; if you are sending a 256 bit message, and get a 256 bit reply, the obvious way using OTP would be the message to use up 256 bits of pad, and the reply to use up a separate 256 bits of pad, using a total of 512 bits.

Instead, you propose to use a total of 512 bits to send the message (and a temporary pad), the reply will then be encrypted using the temporary pad); this uses a total of ... 512 bits of pad.

Well, I don't see any reasons why this would be insecure (however, you appear to think you have a way to extend this to multiple messages; exactly how that would work is not obvious), however I also don't see any specific advantage over normal OTP; in both cases, you're using 512 bits of pad to transmit a total of 512 bits of message.