Adding a device to middev

Does anyone know how to add a new MIDI device to a middev XML file and then have Audio MIDI Setup recognize it?

I'm using OSX Maveriks 10.9.1.

For those interested in a little background. 😝

I have an old Ensoniq SQ-2 Keyboard. The middev file for this device is located in Library/Audio/MIDI Devices/MOTU/Ensoniq/Ensoniq.middev.

However, I want to change the default patch names for this device by keeping the old device but creating a new one that will include my new patch names.

I can attempt to create a new device by copying an already existing one in the middev file (making sure to include the opening and closing XML tags intact) and pasting this copy back into the file.

However, when I then open Audio MIDI Setup, the only devices that seem to be available are all those up to the point at which I inserted the new device into the middev file.

If I keep the original file but change just the name of the device, once again Audio MIDI Setup only sees all devices up to the changed device. 😢

Ideas? 😕

Thanks

-Mike