 <p>You can just update the object</p> <pre><code>string filmID = comboBox1.SelectedValue.ToString(); Scenario newScenario = new Scenario(); foreach (Scenario scenario in myDatabase.Scenario .Where(scn =&gt; scn.filmID.ToString().Equals(filmId)) { scenario.SceneWriter.Add(newScenewriter);before } myDatabase.SaveChanges(); </code></pre>