I think that the direct-indirect order should be used for this situation. I would first remind the temporary employees that this job was stated as a temporary job and that this is what they signed up for. Since there is bad news to share along with some good news. I would introduce the bad news first that their employment is ending due to the job almost being completed. Even though it is bad news that they are being let go, I would then share a little good news that they will be asked to come back when there are projects that will require more help. I would think that all temporary employees understand that temporary does not mean permanent. I think that Cher can help promote goodwill by expressing her gratitude to each employee for their contribution to the company and to the project. I would explain that there is not work for them at the moment but as soon as projects come in they will be the first to know and be invited to apply