Hi

You cannot setup a Beam and Play 1’s as front speakers together. 

Roams nor any Sonos portable speaker cannot be used in a Sonos home theater in any capacity.

Regarding your DVD’s...are they DVD Movie disc with DTS sound or are they DVD-A (DVD Audio) discs?

How are the Play 1’s normally used as surrounds or s a stereo pair? 

It is perhaps easier to first say that a Sonos Home Theatre device - (Arc, Beam, Ray, Amp etc.) can only be ‘bonded’ to two rear left/right surrounds and a Sub (or two Subs in some cases). The HT devices all cater for the front left/right/center channels and no further devices can be added to that ‘bonded’ Sonos ‘room’. 

The next thing to note, is that none of the Sonos portable/rechargeable battery products (Move, Move 2, Roam, Roan SL) can be used as part of a bonded HT setup - so no these  (Roam) speakers cannot be used for Sonos rear surrounds, or indeed for front left/right channels.

Additional speakers however like Roams etc; can be ‘grouped’ with Sonos HT rooms. See this link on how to group/ungroup Sonos devices…

https://support.sonos.com/en-us/article/group-and-ungroup-rooms

Note: ‘Grouped’ and/or ‘Bonded’ Sonos rooms all play in perfect sync for music audio, but if playing TV audio to a grouped room, there is a ~75ms audio buffer delay to each and every grouped room, meaning that the grouped room, such as ‘Roams’ will not be in sync with the HT speakers, by default.

However there are tools in the Sonos App designed to buffer the TV HT audio to try to bring the HT room in sync with any grouped rooms - but that in-turn may introduce lip-sync issues with any video on screen. There are buffering options too to prevent audio dropouts across grouped rooms. To perhaps understand a little more about these Sonos tools, maybe see these Sonos support links:

https://support.sonos.com/en-us/article/tv-audio-and-video-are-out-of-sync

https://support.sonos.com/en-us/article/tv-audio-stops-or-skips

Thanks for the assistance on this. 
 

so essentially the play 1’s remain as either stereo or surrounds for the beam 

the roams just become additional speakers so no 5.1 style system. 
 

The Beam with the two Play:1s bonded to it, is a DD/DTS 5.0 setup - you would just need to add a Sub (or two) to make it a 5.1 HT surround sound system … to which you can then group Roam(s) or other Sonos speakers etc. Up-to 32 Sonos products in total can be used in a single system/household.

The Beam is a 3.0 speaker.

Adding the 1s gives you 5.0.

A Sub or Sub-mini would add the 0.1

I’d set your Roams up as a stereo pair placed to give your usual listening position an optimal stereo image for music listening. If you want more volume, but poorer imaging, Group the Beam Room to the Roams and set teh surrounds to Full Mode.