There's no way the 100s are connected to the Beam by Bluetooth.  The Beam does not have Bluetooth capability.  You can't use the 100s as front speakers with a Beam because the Beam already covers the front left, right, center.  You could group the 100s with the Beam, but there will be an echo repeating the front channels on the Beam.  If you delay the Beam to get rid of the echo, you will have lip sync problems.

In short, the only way to effectively use the Era 100s with a Beam is as surrounds.

Thank you. You said 100s but does the same apply to 300s? Why can I do it for music but not for regular TV?

Any Sonos speakers will be delayed when grouped to a Sonos soundbar.  The reason is because the soundbar needs to play almost immediately to keep in sync with the TV.  Sonos had to develop a low latency, one way, direct 5GHz connection between the sounbar and the surrounds/Sub to keep those all in sync.  This connection is low latency, but not robust, and it doesn't do well through walls or floors.  Which is fine, because a soundbar, surrounds and sub are all in the same room.

Grouped speakers, on the other hand, can be placed anywhere Iin the home.  Therefore, they need a larger buffer, and the more robust 2,4 GHz signal.  This is why speakers grouped with a soundbar have an echo.  They lag behind due to the buildup of the buffer.  With music, i there's no need to sync with the video, so all units in the group are buffered.