Here are some details copied from Sealife's shipping rules.
Sealife tries to accommodate clubs and group orders to help defray shipping costs. The group coordinator must place an initial order and pay for the shipping costs as a normal order and include the group name and any group requests in the comments section. Subsequent orders may select the Prepaid Shipping: Group Buy option from the Shipping Options menu on the Delivery Information page and provide the group name and original order id on the Payment Information page. All Group Buy payments must be completed through Paypal.
So, one of us, presumably Barb (Newreef2) will make the original order and pay shipping. Then, each of us will place our order directly with Sealife. Barb will divide the shipping costs among those of us placing an order and we'll pay her our share of shipping when we pick up our order. We will have already paid for the order itself. Is that the way everybody understands it?