Too large a group may make the working unfocused, feel free to experiment tho. If you have a shared memory, mention it and bring that into your mind. Don't try to focus on it, just hold it there and it will unfold. If you have no specific starting memory to work from, just still yourselves, and intend together to remember a time when you were together. Memories should surface of their own accord, do not try to force them.
Meditation is a very useful tool for inner discoveries of any kind.
When you do, you will find your inner self joyfully sharing it's secrets. Meditation Eyovah got this from another list. Get yourself comfort sitting on the floor or bed or the ground outside. Relax, calm down and gaze at the water. Think of the water moving and flowing, then think of the flow and ebb of time.