FYI - Just found out today that a new B2B SCA normalized message property b2b.dynamicDC can be used to override the "TO_PARTY" delivery channel in the agreement. So, from a BPEL process, set the b2b.dynamicDC property with a value equivalent to your desired "Trading Partner" delivery channel name. Note: make sure to surround the value with quotes. E.g. b2b.dynamicDC="Delivery_Channel_Name". When the business message is processed, the default Delivery Channel in the agreement will not be used and the override value will be used to encrypt/sign/send the message.