Two identical speakers can be “Bonded” as a stereo pair. Single speakers, Pairs, and Surround setups each becomes a “Room”. You can “Group” Rooms to play the same music.

I’m not sure what you are attempting.

I have a similar question, I moved 2 Ones from my Living Rm Surround to my basement (temporarily).  Ideally, I wish they would have just continued playing the Living Rm sound but they do nothing.  I can’t add them to the basement group, I can’t see them at all.  As far as the app is concerned, they no longer exist.  I can’t get them connected to anything at this point.  

If you just moved them without first using the app to “remove surrounds”, you may have moved them out of range of the soundbar’s wifi range. Thus the app still won’t recognise them on the wifi. 

Sounds about right, I put them back in their original location, that moved things in the right direction, got it figured out now.  Thanks!  

Note that ‘surrounds’ get a signal from the Sonos soundbar, but when not being used as surrounds, the speakers connect to WiFi/SonosNet/ethernet cable.