Wiring Echo to Sonos - will it play on a group?

Hi, 

I recently bought my first Sonos speaker (Sonos 5) and I’ve plugged it into my Echo Dot (via a double-ended 3.5 cable) so I can hear Alexa and use her to play Spotify Premium.  It seems to work well.  

I'm now thinking of adding a sub and a couple of Sonos 1's, but before I do wanted to check whether these additional speakers will also 'connect' to Alexa and play nice.  Obviously, only the 5 will be wired to the Echo, but will it send the audio it receives from the Echo to the additional speakers?

If the answer is no, then perhps one of the Sonos 1's I get should be the model with Alexa built-in, in order to get Alexa to play Spotify to the group?  In fact, I suspect this setup would likely be better than wiring to an Echo?

Justin checking before I add more speakers and find out it won’t work with Spotify/Alexa to void disappointment.

Many thanks!