Hi there,
From what I rememember and this is going back 9 years!! so sorry if my memory is lapse, but it is very similar to a cabin crew interview, as both use customer service skills.. I remember about 10 of us around a table and given a problem to solve and each of us had part of the solution or more details of the problem in small individual cards.. It is important to interact and involve everyone and not just dismiss someones else opinion..I got the ball rolling and said why dont we all read out our cards to everyone else ans see what other info or options we have ( l i got through to the next stage, but turned down the job in favour of flying at the time) so maybe this approach helped.. I cant remeber what else happened on the day but hope this helps.
In short, don't say to little, dont speak over someone, listen!! clarify if need be, smile and try and enjoy it..In the end the experience is all good and I took that with me for other interviews. Fingers crossed for your friend!