Swapping order of two HL7 segments in outgoing message

 So, I think this can be done but cannot remember how.

Inbound message goes:

MSH

PID

PV1

ZIF

OBX

We want outgoing message to be 

MSH

PID

PV1

OBX

ZIF

Do I need to create a new schema to make that happen?

Thanks,

Tim