It is now possible and easy to connect your Amazon Echo speakers for multi-room play back,
Here is how;
Make sure you have them all on the same WiFi network, you also need to have Amazon Prime Music or Music Unlimited. To have more than one stream at once you do need to have a family plan with Music Unlimited. Multi-Room playback also supports Pandora, iHeartRadio, SiriusXM, Spotify and TuneIn.
Unfortunately Multi-Room playback is not possible over Bluetooth, if you do have a Bluetooth speaker you will have to connect them using the 3.5mm jack. I tend to connect my phone to the speakers via Bluetooth so this was a small drawback for me.
Now to getting it set up
Go to your Alexa App
Go to Settings
Scroll down to Multi-Room Music
Click on Multi-Room Music
Press on Add Group
Press on Amazon Multi Room Music Group
Name your Group and press Next
Click on all the speakers you want to connect and press save
A screen will up that says Connecting your Echos..