Blu toof tauk

Will Pair to phone,
Will Pair to Stereo Adapter
Will Pair GPS Nav.
If it's Bluetooth, it will pair.

A tad more involved than the dual set:

The LX-R6 can be paired with up to five other headsets for intercom communications.

To pair, turn on two headsets that you would like to pair, These will be the A&B sets, press and hold the B button on headset A for six seconds until the LED flashes red and blue alternately. Meanwhile, press and hold the A button of headset B for 6 seconds until the LED flashes red and blue alternately. 
Short press button A of headset B, or the B button of headset A and wait until connected. 

Then you may pair headset A to C, A and D, A and E, A and F, then B and C, B and D, B and E, B and F, then C and D, A and E, C and F, then D and E, D and F. Then Headset E and F by following the same procedure.

Got that?