Как организовать сложную таблицу

Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        DataGridView1.Columns.Add("Day1", "День")
        DataGridView1.Columns.Add("Night1", "Ночь")
        DataGridView1.Columns.Add("Day2", "День")
        DataGridView1.Columns.Add("Night2", "Ночь")
        DataGridView1.Columns.Add("Day3", "День")
        DataGridView1.Columns.Add("Night3", "Ночь")
        DataGridView1.Columns.Add("Day4", "День")
        DataGridView1.Columns.Add("Night4", "Ночь")
        DataGridView1.Columns.Add("Day5", "День")
        DataGridView1.Columns.Add("Night5", "Ночь")
        DataGridView1.Columns.Add("Day6", "День")
        DataGridView1.Columns.Add("Night6", "Ночь")
        DataGridView1.Columns.Add("Day7", "День")
        DataGridView1.Columns.Add("Night7", "Ночь")
        For j As Integer = 0 To DataGridView1.ColumnCount - 1
            DataGridView1.Columns(j).Width = (DataGridView1.Width - DataGridView1.RowHeadersWidth - DataGridView1.ColumnCount / 2) / DataGridView1.ColumnCount
        Next
        DataGridView1.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.EnableResizing
        DataGridView1.ColumnHeadersHeight = DataGridView1.ColumnHeadersHeight * 2
        DataGridView1.ColumnHeadersDefaultCellStyle.Alignment = DataGridViewContentAlignment.BottomCenter
        AddHandler DataGridView1.CellPainting, AddressOf DataGridView1_CellPainting
        AddHandler DataGridView1.Paint, AddressOf DataGridView1_Paint
    End Sub
 
    Private Sub DataGridView1_Paint(sender As Object, e As PaintEventArgs)
        Dim monthes As String() = {"Понедельник", "Вторник", "Среда", "Четверг", "Пятница", "Суббота", "Воскресенье"}
        Dim j As Integer = 0
        While j < DataGridView1.ColumnCount
            'get the column header cell
            Dim r1 As Rectangle = DataGridView1.GetCellDisplayRectangle(j, -1, True)
            r1.X += 1
            r1.Y += 1
            r1.Width = r1.Width * 2 - 2
            r1.Height = r1.Height / 2 - 2
            e.Graphics.FillRectangle(New SolidBrush(Me.DataGridView1.ColumnHeadersDefaultCellStyle.BackColor), r1)
            Dim format As New StringFormat()
            format.Alignment = StringAlignment.Center
            format.LineAlignment = StringAlignment.Center
            e.Graphics.DrawString(monthes(j / 2), DataGridView1.ColumnHeadersDefaultCellStyle.Font, New SolidBrush(Me.DataGridView1.ColumnHeadersDefaultCellStyle.ForeColor), r1, format)
            j += 2
        End While
    End Sub
 
    Private Sub DataGridView1_CellPainting(sender As Object, e As DataGridViewCellPaintingEventArgs)
        If e.RowIndex = -1 AndAlso e.ColumnIndex > -1 Then
            e.PaintBackground(e.CellBounds, False)
            Dim r2 As Rectangle = e.CellBounds
            r2.Y += e.CellBounds.Height / 2
            r2.Height = e.CellBounds.Height / 2
            e.PaintContent(r2)
            e.Handled = True
        End If
    End Sub