Actually, Priya gave the impression that they were all in a group or alliance after Travis came back from the Sanctuary by telling him they had a full group again. She then went and used her power play to give everyone in this "group" points to get them up for nomination while giving no points to people not in the group, which I said makes no sense to me.
That being said, I believe it is probably hard for them to form any kind of true alliance because they can't talk to each other about who they nominate which I think totally defeats the "game" purpose of Big Brother. How can they be strategic and make alliances if they can't even discuss who they're going to vote for with their alliance?