Firmata with multiple Arduinos


I am quite new with arduino programming and for my university degree I am making a modular DAW control surface using multiple Arduinos to read values from sensors into puredata and translating them to OSC for REAPER.

I got communication going from one Arduino to puredata using Firmata and pduino patch but as I am making it modular (having more than one Arduino) I need to add some kind of ID to be sent with each message. What I am going to try is to read messages with serial monitor to see what exactly is firmata sending.

So my question is, does anyone know how to implement the device ID using Firmata? Or maybe any other suggestions how to implement this?

Ohh yes and I am using ciseco radio modules to send data between arduino and PC.

EDIT: Just figured that I could change the start of SysEx for each device different (default for Firmata is 0xF0), would that theoreticaly work?