How do you pair two Cortana Invokes ?

[OHardy]

I bought one pearl white Invoke 3 days ago & yesterday the Phillips Hue hub & bridge kit which works well. I needed another for my bedroom, so today I purchased the black one & would like to pair it with the other Invoke for a seamless integration of Cortana.

 

[RalphieD]

Also interested in this, since i was thinking of adding one to the second floor of my house.