Asking how to set up a creative group is only one half of the picture. Creative thinking occurs in context and varies and is responsive to context.You also have to have a good analysis of what tools and materials are available to you and what the time frame is and what degree of precision with which you need to effect the desired changes - maintain the status quo. (I am avoiding saying 'solve the problem'because that is a kind of metaphor which may not always apply.) Also one assumes a creative group would have a client, the prson who wants some kind of change. Communication with the client IMO is about 90% of the challenge - cf trying to set up a database for someone - they usually don't knowwhat they want, what they want to do or what they could do and are likely to change their minds half way through.
Actually I think a creative group would have to go through a very similar process to that of someone designing a database for a client. This problem - of trying to find out exactly what they want - is convergent, not divergent - there is one optimum way to do it. Once you get this right, you have found the constraints for the topic (I am trying not to say 'problem',because it may not be one). Then you could list the possible permutations of the topic features - the ones that are apparnt the goups anyway. This would be a process similar to fault testing - you check through the possibilities. Another way of expressing this would be to say Methodically check out all possible algorithms you can think of (knowing your list will likely be incomplete.)
Now when you have exhausted all the obvious, methodical donkey work, then you can become creative by going back and reconsidering all the possibilites you previously discarded, because some of them may work after all with a tweak or a reframing.
I suppose I am suggesting a meta-algorthim here. I actually believe there is a solution to any problem -i.e thee is always a way forward for a human being or a human group, but the problem may have to be radicallly reframed. But I don;t think you ever actually have to conceptualize yourself as being forced to 'give up'. I think this attitude/ viewpoint is vital to creativity - because you wanted todo the work involved unless you believe it will pay off. As the Romans said They can because they believe they can. Long comment but complex question