How to convert an excel sheet to a specific format in ASP.NET

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C#

ASP.NET

Excel-2016

how to specify 6 columns and name them in datagridview so when i import an excel sheet with missing columns it adds the missing columns, keep the content empty and arrange the columns based on what i specify in datagridview note: column name does not change

for example i specify column A,B,C,D in datagridview the excel sheet it has the same column name but some of them are missing for example (A,C)

What I have tried:

this is what i did for importing excel sheet in to the application

using ExcelDataReader;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

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

        private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog fil = new OpenFileDialog();
            fil.ShowDialog();
            string path = fil.FileName.ToString();
            ExcelFileReader(path);
        }

        public void ExcelFileReader(string path)
        {
            var stream = File.Open(path, FileMode.Open, FileAccess.Read);
            var reader = ExcelReaderFactory.CreateReader(stream);
            var result = reader.AsDataSet();
            var tables = result.Tables.Cast<DataTable>();
            foreach(DataTable table in tables)
            {
                dataGridView1.DataSource = table;
            }
        }
    }
}