I’m confused by your post.

If you want surround speakers with your Beam you’re creating a 5.0 system. Where does mono sound come into that? And why will Amp be different to the Play:1’s? If you only have a mono source there is no “surround” data to play. Or, if it’s a music source, set the surrounds to Full rather than Ambient for music playback and you should get music from them and the Beam.

A Play:1 is perfectly capable of playing a mono signal. If you have them (or pretty much any speaker/amp sets) set up as a stereo pair, a mono  music signal should play the same sound from both speakers. But stereo-paired is not the same as bonded to the Beam. 
 

If you have the Play:1s or Amp bonded to the Beam as surrounds, they will always act as surround speakers and play the left and right surround channels when playing TV audio. If you want the Play:1s to act as mono speakers, unbond them from the Beam and group them with the Beam in the Sonos app. The Play:1s will play TV audio as mono speakers, BUT you will probably experience a slight audio delay.

Sorry it was late, let me take another go at explaining. The beam is connected tot he tv via hdmi. The amp is connected to the outdoor sonance speakers 20 ft away on either side. Because they are far I want the sonance to play mono (same audio as the beam) and not act as surround audio. Maybe I don’t I’d wear and how to “bond”, currently in the app the beam is one room and the amp is another room. The only way I can see to merge them is add them as surrounds which is not playing mono.

As already suggested, when the Amp is ‘bonded’ to the Beam as surround speakers, it receives the surround data, and not a ‘mono’ replication of the data sent to the Beam. 
 

You could choose to not ‘bond’ the Amp to the Beam, but instead set it up as a separate room, and use the ‘group’ function to send the data that’s playing in the Beam’s room to that Amp. However, as explained, there will be a slight delay between the sound coming from the Beam and the sound coming from the Amp, at a minimum of 75ms, due to the nature of the way Sonos works. This delay would only occur on data sent to the Beam on the HDMI input, if you were to stream a music source, both rooms would be in sync.

Sonos software doesn’t really have the capability to do what you want to do, unfortunately. There have been requests very similar over the years, most often associated with the hard of hearing, who want a secondary duplication of that ‘front’ set of channels in a second position, like in ‘rear’ speakers.

Have you considered removing the Beam and connecting the TV directly to the Amp? This is how I have things setup in the backyard.  TV sends audio to the Amp via HDMI-ARC, and Amp powers two pairs of speakers in the back yard.  No need to use a Beam outdoors where it’s not made to be used.  Amp stays inside.

This won’t work if  you can’t wire an HDMI cable between your TV and amp, but then, there isn’t going to be a good wireless solution.  There may be some wireless HDMI solution that will work, but doubtful on that.

Thanks all.

@Airgetlam this is kind of what I suspected. Are you able to direct how I do the group function, I do not see that in the app.

alternatively, would it be possible to use a hdmi splitter. So the hdmi arc going out of the tv could feed both the amp and beam separately to kind of trick it to being different rooms but have the same source audio?

https://support.sonos.com/s/article/3391?

I’m personally not fond of splitters, they more often than not mess with the level of voltage provided. And you’d need to find one that deals with ARC specifically. since you are technically not splitting the source signal, you are splitting the ARC signal from the TV set.  I suppose you could try it, but you’re getting way out of my own personal comfort level for giving advice. It’s certainly not a use as the system was designed. 

If your TV has an optical input, you can get a splitter for that.  The Beam comes with an ARC to optical converter, and you can buy a second one for the amp.  Optical can’t carry the higher audio codecs, but that likely won’t be a concern for you setup.  The other issue is that you are limited to wire length with optical.

Another option,  if your  source is an cable box or streaming box, not an internal TV app, then you can put an HDMI splitter  before the TV.  One line goes to TV and Beam, the other goes to  HD Fury Arcana or similar (which converts HDMI to HDMI-eARC signal) and then to your Amp. Or , instead of Arcana, just put a 2nd TV in the backyard, connected to your Amp.