Sync two One SL's with a Beam?

Hello,

My dad has a Beam, and he was having trouble hearing the voices on it. So we recently got him two One SL’s, one of which we figured could go next to his chair.

We quickly realized setting up the One SL’s as surround sound wasn’t the answer, as voices still come out of the Beam mostly.

I can group the Beam and the One SL’s to play in sync, but it has to be manually tirggered at each One SL every time, by long pressing the Play button on each, when you turn the TV on.

I’d like each One SL and the Beam to always be in sync when he turns his tv on, so he can hear it better. Is it possible to set them up in a group so it plays that way by default? 

Thanks!