Hello Benyamin,
Regrettaly at the moment, the Chat module doesn't support groups and there is no relationship created in this way. I'm really sorry.
On the other hand, if you want functionality like this available in the feature version of Kentico, you can suggest it and also other users will be able to vote for it (more users = higher priority), on the special page: Kentico UserVoice
Regards, Martin Danko