None of the group buys I've been involved in have functioned in this manner. I think the way to do it is for one trusted person to finalize the order, get a quote from NCM, post totals, collect Paypal payments from each brewer, and submit one final payment to NCM. We don't want to irritate them and risk losing the group buy opportunity.
The last one from NNJ was like that from what I remember, about 6 months ago.