如何将Excel模板复制到相同Excel中的另一个工作表

我是OpenXML的新手。我的概念不完全清楚。我使用以下代码-

Package package = Package.Open(newFile.FullName, FileMode.Open, FileAccess.ReadWrite);
            excelDoc = SpreadsheetDocument.Open(package);
            WorkbookPart wbPart = excelDoc.WorkbookPart;
            Sheet templateSheet = wbPart.Workbook.Descendants<Sheet>().Where((s) => s.Name == "Sheet1").FirstOrDefault();
            for (int i = 0; i < (int)(obj.Count / 4); i++)
            {
                WorkbookPart workBookpart = excelDoc.WorkbookPart;
                Workbook workbook = workBookpart.Workbook;
                Sheets sheets = workbook.Sheets;
                WorksheetPart workSheetPart = excelDoc.WorkbookPart.AddNewPart<WorksheetPart>("workSheet" + (i+2));
                Worksheet worksheet = new Worksheet();
                SheetData sheetdata = new SheetData();
                worksheet.Append(sheetdata);
                workSheetPart.Worksheet = worksheet;
                sheets.Append(templateSheet.CloneNode(true));
            }
            for (int i = 0; i < (int)(obj.Count / 4); i++)
            {
                uint sheetId = 1;
                if (excelDoc.WorkbookPart.Workbook.Sheets.Elements<Sheet>().Count() > 0)
                {
                    sheetId = excelDoc.WorkbookPart.Workbook.Sheets.Elements<Sheet>().Select(s => s.SheetId.Value).Max() + 1;
                }
                Sheet temp = wbPart.Workbook.Descendants<Sheet>().Skip(i + 1).Take(1).FirstOrDefault();
                temp.Name = "Sheet" + (i + 2);
                temp.Id = "workSheet" + (i + 2);
                temp.SheetId = sheetId;
            } 

此代码正在创建工作表，但模板不存在，存在于"Sheet1"。我该怎么做呢?请建议。