@Soloman 

Of course you would be able to run the Beam2 and Play1s together in a S2 system. The P5 Gen1 isn’t compatible with S2. So you would have to use separated systems. If you updated your S1 system to S2, you might have to follow the steps described in the support document. 
https://support.sonos.com/en-us/article/set-up-separate-s1-and-s2-sonos-systems

Thanks for the reply, I really appreciate it.

Great news, so,  I need to disconnect the Play1’s from my S1 system before I can connect the. To the S2, yes?
I did not want to disconnect previously  as I was a bit gun shy about what happened to my orphaned Play5.

Any advice on how I can get my Play5 back on to the S1 system?

thanks again.

Plug it back in to power, and fire up the S1 app. The two operating systems can coexist on your controller and network, but it’s just easier to unplug one system while setting up the other. 

Thanks everyone,
I am back in action, I have sono1 and 2 running,.

Sonos2 running with the beam and 2 of my old play1”# as surround sound.

Sono1 Play5 back, reset and reconnected.

I have  1 remaining   Play1 unfortunately got upgraded for sonos2 and I would like to add to my Sonos1 system. The factory reset does not go passed the flashing amber phase, it does not reach the flashing green.

So I am almost there I just need to get this downgrade going, I think?

@Soloman 

Reset your Play1 as described here…

https://support.sonos.com/en-us/article/reset-your-sonos-product
 

Be aware some time ago Sonos had to change the way older products will be factory reseted because of hardware limitations. That also means that it takes much longer like in the past. Please wait for about 30 Minutes for the green flashing light.

After the reset please follow instructions on support document to downgrade Play1 to S1 firmware.

https://support.sonos.com/en-us/article/downgrade-a-sonos-product-from-s2-to-s1

Thanks once again,

I have waited o’night for the green flashes. Looks like I will next try the Ethernet cable.

Good idea…

I sort of had the same issue when trying to join a Play5 Gen1 speaker to my existing system.  This is what I wound up doing and this may not be applicable to everyone.

1. dig up old wireless router (mine was an old Linksys WRV-54G)
2. add the wireless router to my existing home network (need to re-IP to ensure the router does not use an existing IP address as well as disable its DHCP server)  Also do not use the Internet port.  Just connect to home network using an internal port.
3. setup a new SSID (I used Sonos-Setup as the SSID)
4. Connect my tablet to the temporary SSID
5. Connect my Play5 to the old wireless router via ethernet cable
6. Once Play5 was connected, disconnect from the wireless router and reboot the Play5 to ensure it joins the Sonos network via wireless
7. I turned off the old wireless router (saving it if I need to add any more Gen1 or Gen2 Sonos devices to my Sonos S1 system.

This allowed me to add the Play5 Gen1 to my existing system.  I admit it is a not so straight forward thing but it did work.