To send the tuner information from your G-Major to the G-Minor, you need to connect the MIDI out from the G-Major or G-Force to the MIDI in on the G-Minor. Make sure that in the G-Major's Utility menu, you have set the "Send Tuner" setting to "ON".
You will only see the tuner information when you switch the G-Minor to tuner mode. Please refer to the manual for more information.
You can use the MIDI out of the G-Major of course to do a bulk dump of your preset settings into another device or sequencer, or to make a backup of your presets.
The MIDI in on the G-Minor could also be used if you would like to cascade several G-Minor's to have more control. The Midi DATA will me merged together with the G-Minor output.