Yes, you can group the two, with one caveat - The One will lag behind the Ray for TV sources.  This is not noticeable when they are in different rooms, but it will affect the sound when they are in the same room.

Yes, and no. :)

You can certainly “group” the two rooms, one the Ray and the other the Sonos One. However, due to the way that Sonos works, the sound from any “grouped” room with the Ray will be delayed by at least ~75 ms. So if it’s in another room, not really a problem. I used to do this with some PLAY:1s in my kitchen during football games, back when I wasn’t in a open floorplan. 

But I’ve found that if that “grouped” speaker is hearable (read: in same physical room as) at the same time as the Ray, it’s too much like a stadium speaker when someone is trying to sing the national anthem. The delay is just too much for me to deal with. 

That’s me. You could try it and be happy with it, my position is not to judge, just to give information. 

Most people use a par of Sonos Ones (or in my case, the PLAY:1) as surround speakers, by “bonding” them to the Ray, but then they play surround information, and not the same center channel that contains voice, and that is, what I think, you want to do. 

You could indeed group them, turn down the volume on the Ray, and have the One turned up, though….you’d just have that minor lip sync problem with the video. 

Edit: Noted that I’m a slower typer than @jgatie :)

Note that I’ve used specific terms. In the Sonos context, there’s quite a difference between the terms “Paired”, “Grouped” and “Bonded”.

Paired means two (like) speakers set up in stereo. e.g. a pair of Sonos Ones, where one is left, the other is right.

Grouped means any number of Sonos rooms, playing the same content. Due to the way that Sonos is designed to work, any streamed music content will be in sync, but any TV generated content will be delayed by around 75ms in any other room than the original.

Bonded means a speaker that is tied to another speaker in a special way. Examples of bonding are a Sonos Subwoofer, which is always tied to another Sonos device. Or surround pairs, which are always tied to the front of the home theater room’s device.