No, unfortunately not. In order to bond surround speakers, they both need to be the same speaker type. Additionally, the portable speakers (Roam and Move) can not be used as surrounds. In your case, if you got another Era 100, you could bond both with your Sonos Ray as surround speakers. 

Thanks Bruce,

So, I need the 2 roams I already have plus 1 Era 100 sonos?

Not simply 1 roam and 1 Era 100?

As I think I already said, the Sonos Roam can not be used as a surround speaker. You will need a second Era 100 to go with the one you have in order to ‘bond’ it to whatever Sonos Home Theater device you’re using. 

You can use you’re two Roams that you already have anywhere you would like. 

Why is my Roam's sound cutting in and out? Is that common

Deeneez You might start your own topic and give us more details on your setup, normally the Roam works just fine.

Thanks Stanley_4.  My Sonos Ray is Optical line into my LG tv. The Sonos Roam is wifi / Bluetooth into that. 

The Roam does sputter...