Yes it’s easy - set the Ones up as two separate Sonos rooms and in the Beams ‘room’ settings (in ‘Settings/System’ in the App) you can both add and remove them as HT surrounds.

When they have been removed from that setup afterwards, just put them in your conservatory and stereo ‘pair’ them from the ‘room’ settings of one of the Ones (usually best to start the pairing from the left speaker).

Note: you have to remove the stereo ‘pairing’ before adding them again to the Beam (just in case you decide to put them back again in that room). 

Thanks for the reply, is it easy to remove stereo pairing and then trying it on the beam ,also would need to somehow remove the surround set up before  re adding stereo pair ,is it not possible to set up the beam in the living room and stereo in conservatory with the same speakers so they work with either depending what I select on the app ,meaning if I physically put the speakers in living room will the beam on the app pick them up and vice versa 

You would have do this in two completely separate steps. First you would need to ‘unpair’ the two stereo speakers and then ‘bond’ them both to the Beam - each step takes around 30 seconds or so, but note if you have previously Trueplay tuned either the ‘paired’ or ‘bonded’ room, you will lose those settings and it takes about 5 minutes to retune each room. You do not have to tune a Sonos room, but it may not sound as good (arguably) - it requires a compatible Apple iOS device to tune a room.

Yes you need to ‘unbond’ the surrounds from the Beam, before you can ‘pair’ the Ones together.

In this instance, it might simply be best to leave the three devices ‘bonded’ together... note however they usually communicate over a 5Ghz ad-hoc wireless connection, so you do not want them too far apart and separated by brick walls etc; as otherwise their ‘bonded’ connection may suffer interference and playback disruption.