How do others post awards for ongoing, long term fixed price bids in Strategic Sourcing?

Our requirement is to create a fixed priced bid event in strategic sourcing, post the event, and receive bids from multiple suppliers. At multiple times throughout the year or time frame of the solicitation, we award the event to several of the suppliers. Then we create contracts for each supplier using the post award process. At this point we want the event to stay open so we can continue to receive bids from future suppliers, then at another date, award several more, post them and create contracts for those suppliers.

In Strategic Sourcing, once you award an event to one or more suppliers and post the award, the event is completely closed. This prohibits the ability to accept future bids.