web service response message as multi-part message

I am running into an issue where a web service is returning four message parts returned in the response schema however when I attempt to send the response message to a send port bound to a file adapter the message that is generated is only the first message part and not the entire response message. 

I've come up with a small helper class to combine the parts into one message since all are xml based but is there a more elegant way around this?