Vendor records and buying groups

We are members of a buying group, through which we gain access to many vendors at a better rate.  There are numerous vendors under the buying group.  When we do business with one of the vendors, the PO and item receipts are handled directly with the vendor, but the invoice and bill pay is handled through the buying group.  Looking for a way to handle this gracefully in NetSuite.  We want to associate these vendors to the buying group so that when it comes time to pay the bill, we can handle this through the buying group's vendor record, rather