They will have to download the Sonos App and you’ll have to give them access to your account. Not recommended. 

A better way is to purchase a Roam2, Move2, Era 100 or Era 300. Those speakers are Bluetooth enabled to allow a cell phone to connect to them. You can setup a permanent Group that includes one of the speakers suggested and all will play the tunes. *

You might also check out Sonos Zones here which is a new feature for grouping but requires specific speakers in order to build a Zone.

 * I recommend the Era 100. No battery and IMO the best bang for the buck!