Yes, if I understand your question correctly. Any speakers assigned to rooms can then be grouped to play together. Streamed music will be totally in sync but there would be a very small delay in tv sound to the Play:1’s but that would only be noticeable if you were in a position where sound levels were equal - standing in the doorway between the two rooms.
Hi. Yes you have understood it. We have a Play1 in the lounge, one in the kitchen diner and want the Beam in the garden room. We will not want the TV playing through all three. I will want to use the Beam separately with the TV and then when entertaining, use all three for the music.
Then that is fine. The Beam can do everything that the Play:1s can do with music sources, either singly or in sync.
In fact it can do more, as it is Airplay 2 compatible.