I had to implement a second Sonos system due to adding a Five and Arc (S2 only) to existing Sonos S1-only speakers.
When setting the speakers up in Alexa one can only choose a single system.
It would be very useful to be able to include more than 1 system.
Sonos could do it by either a) allowing selection of more than 1 system in the existing Alexa skill, or 2) adding a second skill (Logitech does this for its Harmony remotes).