New vs Existing worksheets

I wanted to use the code at this link to add strings to multiple "existing cells" on an "existing sheet". I want to get away from creating new sheets every time I use this code to export a table of strings from my database into my excel report sheet template. Is there a way to modify the code to do overwrites and write many cells at once? I tried for instance naming the sheet without the id number added but that just creates a sheet with the same name that excel then identifies as material to be recovered and it changes the sheet name to something to prevent duplicates. It feels like the code blocks defining the new worksheet and cell locations would have to be changed a lot so I am not sure if this kind of functionality is possible. I would appreciate any pointers to the right solution.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
//first "Add Reference" "Assemblies" named "DocumentFormat.OpenXml" and "WindowsBase"
//needed for using the open xml sdk to insert cells into spreadsheet
using DocumentFormat.OpenXml;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Spreadsheet;
//added this to allow the process statement that opens excel
using System.Diagnostics;

namespace Inserting_cells_into_spreadsheet
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            GeneratedClass gc = new GeneratedClass();
            gc.InsertText(@"C:\Users\Jordan Walker\Documents\DATA sheets\MAR.xlsx", "Hello New World");
            //This opens the excel file from the current directory
            Process.Start(@"C:\Users\Jordan Walker\Documents\DATA sheets\MAR.xlsx");
        }
    }
}
namespace Inserting_cells_into_spreadsheet
{
    public class GeneratedClass
    {
        // Given a document name and text,
        // inserts a new worksheet and writes the text to cell "A1" of the new worksheet.
        public void InsertText(string docName, string text)
        {
            // Open the document for editing.
            using (SpreadsheetDocument spreadSheet = SpreadsheetDocument.Open(docName, true))
            {
                // Get the SharedStringTablePart. If it does not exist, create a new one.
                SharedStringTablePart shareStringPart;
                if (spreadSheet.WorkbookPart.GetPartsOfType<SharedStringTablePart>().Count() > 0)
                {
                    shareStringPart = spreadSheet.WorkbookPart.GetPartsOfType<SharedStringTablePart>().First();
                }
                else
                {
                    shareStringPart = spreadSheet.WorkbookPart.AddNewPart<SharedStringTablePart>();
                }

                // Insert the text into the SharedStringTablePart.
                int index = InsertSharedStringItem(text, shareStringPart);
                
                // Insert a new worksheet.
                WorksheetPart worksheetPart = InsertWorksheet(spreadSheet.WorkbookPart);
                
                // Insert cell A1 into the new worksheet.
                Cell cell = InsertCellInWorksheet("A", 1, worksheetPart);

                // Set the value of cell A1.
                cell.CellValue = new CellValue(index.ToString());
                cell.DataType = new EnumValue<CellValues>(CellValues.SharedString);

                // Save the new worksheet.
                worksheetPart.Worksheet.Save();

            }
        }

        // Given text and a SharedStringTablePart, creates a SharedStringItem with the specified text 
        // and inserts it into the SharedStringTablePart. If the item already exists, returns its index.
        private static int InsertSharedStringItem(string text, SharedStringTablePart shareStringPart)
        {
            // If the part does not contain a SharedStringTable, create one.
            if (shareStringPart.SharedStringTable == null)
            {
                shareStringPart.SharedStringTable = new SharedStringTable();
            }

            int i = 0;

            // Iterate through all the items in the SharedStringTable. If the text already exists, return its index.
            foreach (SharedStringItem item in shareStringPart.SharedStringTable.Elements<SharedStringItem>())
            {
                if (item.InnerText == text)
                {
                    return i;
                }

                i++;
            }

            // The text does not exist in the part. Create the SharedStringItem and return its index.
            shareStringPart.SharedStringTable.AppendChild(new SharedStringItem(new DocumentFormat.OpenXml.Spreadsheet.Text(text)));
            shareStringPart.SharedStringTable.Save();

            return i;
        }

        // Given a WorkbookPart, inserts a new worksheet.
        private static WorksheetPart InsertWorksheet(WorkbookPart workbookPart)
        {
            // Add a new worksheet part to the workbook.
            WorksheetPart newWorksheetPart = workbookPart.AddNewPart<WorksheetPart>();
            newWorksheetPart.Worksheet = new Worksheet(new SheetData());
            newWorksheetPart.Worksheet.Save();

            Sheets sheets = workbookPart.Workbook.GetFirstChild<Sheets>();
            string relationshipId = workbookPart.GetIdOfPart(newWorksheetPart);

            // Get a unique ID for the new sheet.
            uint sheetId = 1;
            if (sheets.Elements<Sheet>().Count() > 0)
            {
                sheetId = sheets.Elements<Sheet>().Select(s => s.SheetId.Value).Max() + 1;
            }

            string sheetName = "Sheet" + sheetId;

            // Append the new worksheet and associate it with the workbook.
            Sheet sheet = new Sheet() { Id = relationshipId, SheetId = sheetId, Name = sheetName };
            sheets.Append(sheet);
            workbookPart.Workbook.Save();

            return newWorksheetPart;
        }

        // Given a column name, a row index, and a WorksheetPart, inserts a cell into the worksheet. 
        // If the cell already exists, returns it. 
        private static Cell InsertCellInWorksheet(string columnName, uint rowIndex, WorksheetPart worksheetPart)
        {
            Worksheet worksheet = worksheetPart.Worksheet;
            SheetData sheetData = worksheet.GetFirstChild<SheetData>();
            string cellReference = columnName + rowIndex;

            // If the worksheet does not contain a row with the specified row index, insert one.
            Row row;
            if (sheetData.Elements<Row>().Where(r => r.RowIndex == rowIndex).Count() != 0)
            {
                row = sheetData.Elements<Row>().Where(r => r.RowIndex == rowIndex).First();
            }
            else
            {
                row = new Row() { RowIndex = rowIndex };
                sheetData.Append(row);
            }

            // If there is not a cell with the specified column name, insert one.  
            if (row.Elements<Cell>().Where(c => c.CellReference.Value == columnName + rowIndex).Count() > 0)
            {
                return row.Elements<Cell>().Where(c => c.CellReference.Value == cellReference).First();
            }
            else
            {
                // Cells must be in sequential order according to CellReference. Determine where to insert the new cell.
                Cell refCell = null;
                foreach (Cell cell in row.Elements<Cell>())
                {
                    if (string.Compare(cell.CellReference.Value, cellReference, true) > 0)
                    {
                        refCell = cell;
                        break;
                    }
                }

                Cell newCell = new Cell() { CellReference = cellReference };
                row.InsertBefore(newCell, refCell);

                worksheet.Save();
                return newCell;
            }
        }
    }    
}