You can group them. 

They will need to be on the S2 controller as the Move 2 will not work on S1. 

Thanks for response- I tried it on Move 2 without success. It will not recognize the Play 3

Have you connected Move to your wifi? And is your Play:3 on the same system?

Are both speakers showing in the new Sonos App? If so, then maybe see the instructions in this Sonos Support link: 

https://support.sonos.com/en-us/article/group-and-ungroup-rooms

Updated app only recognizes Move 2. Play 3 does not show on app at all

You unfortunately can’t group them until both are setup in the same App/System. It’s not clear though, if you’re currently operating your Play:3 in an entirely different Household/System using the S1 Sonos controller App? You may need to switch it to the new Sonos App if that’s the setup you have at the moment and want to group the two speakers together.

Note if you do opt to go down that route yourself, you could (likely) lose the S1 system setup completely, including your music services, settings, playlists etc. so I would maybe take time to consider what you want to do.

There maybe a way to keep your original settings, services, playlists etc; and move the Play:3 to an S2 System if you perhaps speak to Sonos Support Staff and then go onto add the Move 2 to that upgraded system instead.

Here is a link to speak to Sonos Customer Support if you prefer to see if they can assist you to both keep and upgrade your earlier S1 system…

https://support.sonos.com/s/contact

I don’t have any playlists or anything saved to the Play 3- I only connect via spotify and play lists from my phone

Well it is compatible to the new Sonos App according to this link:

https://support.sonos.com/en-us/article/sonos-app-version-compatibility

If it is your only product on S1 and do not mind losing that system, I guess you could factory reset it and add it to the Sonos App as a new device, alongside your Move 2 and then group them.  

Thanks Ken- in the process of resetting- it displayed on the new app and is added as a device- currently installing an update- thanks all for your assistance