In the dbml designer I've set Update Check to Never on all properties. But i still get an exception when doing Attach: "An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported." This approach seems to have worked for others on here, but there must be something I've missed.

        using(TheDataContext dc = new TheDataContext())
        {
            test = dc.Members.FirstOrDefault(m => m.fltId == 1);
        }

        test.Name = "test2";

        using(TheDataContext dc = new TheDataContext())
        {
            dc.Members.Attach(test, true);
            dc.SubmitChanges();
        }