To use as surrounds you must have two matched Sonos.

If you are just Grouping them then all will Group. Grouped do have a delay/echo when playing the TV source.

Thank you for the response! 
so if I don’t use a pair with a soundbar the single speaker would have a delay against the bar, is that correct? That seems like a major flaw if the eco system can’t handle two elements being In sync?

 Not a flaw in the design, meant to work that way.

A TV based Room connects over a dedicated, low latency 5 gHz network to provide synchronized to the picture sound. Soundbar or Amp in front, zero or two Surrouunds and zero, one or two Subs.

Streaming rooms use normal networking to connect and have a buffer designed in to deal with normal networking delays. A TV Room, when streaming operates the same way.

The delay is only when going from the high speed TV Room to normal speed streaming Rooms.

if the beam and the era run only off wifi and not an arc cable there would be no delay? i am trying to see if it makes sense to combine the sound bar with a single 100 at all for music, it seems the tv would be fine just running off the beam.

thank you!

There’s only a delay when grouping a soundbar with other speakers when you feed the system TV sound. Music from the internet is no problem.

So I could run the tv sound via WiFi and it would have no delay or the bar does not accept sound from the tv via WiFi and only arc or hdmi? Thank you!

There are two concepts at work here, bonding and grouping.  Surround speakers are bonded to the soundbar via a low latency, one-way, private connection because they need to be in sync with the video source.  Surrounds can only be set up as a pair, the bond is semi-permanent, and they carry surround channels only.

Grouping is the connecting together of more than one room to play the same source in sync (or slightly delayed if TV is the source).  This requires a buffer in order to pass through walls and floors, thus a grouped room will have a slight 75 ms delay for TV sources that must be in sync with video.  Grouping is not permanent, you can do it on the fly, and grouped room/speaker will play all channels of a music/TV signal, not just surrounds.

Don't think about wifi here, it is not the issue.

If you play streaming audio, all your Sonos will play together, in sync.

If you play TV sound, speakers not part of the Sonos Room will be delayed.

The bar will accept sound from the TV or a streaming source.