Is it possible to allow multiple users to edit each others' listings, but not all listings on t

I have a client using Directory. Everything is working really well, but we have run into a minor complication. Their site is set up for a private group of organizations to use. Each of these organizations can have multiple members who are granted access to the system. They want to set it up so that all users of an organization can edit listings belonging to that organization, but not those belonging to other orgs on the system. Is this possible?