Project owners can add organizations to a project. Navigate to the Info tab in a project's primary horizontal menu, and then to the Organizations tab in the secondary horizontal menu. Click Add to start. A list of available organizations will be listed in the right side of the pop-up. Click on the organization(s) then click Add.
Multiple organizations can be added at the same time. Once an organization is added, team members of that organization can then be added as members to the project.