Not as surrounds, no. You could remove the Sonos Ones as surrounds so they’re set up as a separate ’room’, then group the two rooms together, but then the sound coming from the Sonos Ones would be at least 75ms behind the Beam, which would create an echo like feeling. Not recommended. 

Thanks for your reply. I was hoping to add 2 rears to my beam but am I right in thinking the 2 rear speakers will have no audio coming out of them whilst watching TV stereo 2 0

Yes, you’re correct. In a stereo situation, there is only two channels of information being sent to the Beam, so there is no information to be sent to surrounds. 

And Sonos has not developed any ‘hard of hearing’ mode to assist the people who have been asking for something like this. 

Oh, just to be clear, this is when using the TV input. When streaming music to the Beam, you can certainly set the surrounds from ‘ambient’ to ‘full’, and the surrounds will duplicate the full stereo effect of the music playing on the Beam.