Creating a Custom Group

private void button1_Click(object sender, EventArgs e)
{
    if (fpSpread1.ActiveSheet.Models.Data is FarPoint.Win.Spread.Model.GroupDataModel)
    {
        FarPoint.Win.Spread.Model.GroupDataModel gdm = (FarPoint.Win.Spread.Model.GroupDataModel)fpSpread1.ActiveSheet.Models.Data;
        for (int i = 0; i < gdm.RowCount; i++)
        {
            // Determine whether it is group header row or not
            if (gdm.IsGroup(i))
            {
                // Get group
                var g = gdm.GetGroup(i);
                // Get the reference column of the group and the number of rows included in the group
                Console.WriteLine(string.Format("Column index：{0}, Row count：{1}",g.Column, g.Rows.Count));                       
            }
        }
    }
}

Private Sub button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    If TypeOf FpSpread1.ActiveSheet.Models.Data Is FarPoint.Win.Spread.Model.GroupDataModel Then
        Dim gdm As FarPoint.Win.Spread.Model.GroupDataModel = DirectCast(FpSpread1.ActiveSheet.Models.Data, FarPoint.Win.Spread.Model.GroupDataModel)
        For i As Integer = 0 To gdm.RowCount - 1
            'Determine whether it is group header row or not
            If gdm.IsGroup(i) Then
                ' Get group
                Dim g = gdm.GetGroup(i)
                ' Get the reference column of the group and the number of rows included in the group
                Console.WriteLine(String.Format("Column index：{0}, Row count：{1}", g.Column, g.Rows.Count))
            End If
        Next
    End If
End Sub

[Serializable()]
public class MyGroupComparer : System.Collections.IComparer
{       
    public int Compare(object x1, object y1)
    {
        int x=0, y=0;
        if ((x1) is DateTime)
        {
            x = ((DateTime)(x1)).Year % 10;
            x = ((DateTime)(x1)).Year - x;
        }
        if ((y1) is DateTime)
        {
            y = ((DateTime)(y1)).Year % 10;
            y = ((DateTime)(y1)).Year - y;
        }
        if (x == y) return 0;
        else if (x > y) return 1;
        else return -1;
    }
}
// Write the following code in the code behind of the form
private void Form1_Load(object sender, EventArgs e)
{
    // Enable grouping
    fpSpread1.AllowColumnMove = true;
    fpSpread1.ActiveSheet.GroupBarInfo.Visible = true;
    fpSpread1.ActiveSheet.AllowGroup = true;
    // Set test data
    fpSpread1.ActiveSheet.SetValue(0, 0, DateTime.Today);
    fpSpread1.ActiveSheet.SetValue(1, 0, DateTime.Today.AddYears(1));
    fpSpread1.ActiveSheet.SetValue(2, 0, DateTime.Today.AddYears(11));
}
private void fpSpread1_Grouping(object sender, FarPoint.Win.Spread.GroupingEventArgs e)
{
    var colIndex = e.SortInfo.Last().Index;
    // Generate custom group in first column
    if (colIndex == 0)
    {
        e.GroupComparer = new MyGroupComparer();
    }
}

<Serializable>
Public Class MyGroupComparer
    Implements System.Collections.IComparer
    Public Function Compare(x1 As Object, y1 As Object) As Integer Implements IComparer.Compare
        Dim x As Integer = 0, y As Integer = 0
        If TypeOf (x1) Is DateTime Then
            x = DirectCast(x1, DateTime).Year Mod 10
            x = DirectCast(x1, DateTime).Year - x
        End If
        If TypeOf (y1) Is DateTime Then
            y = DirectCast(y1, DateTime).Year Mod 10
            y = DirectCast(y1, DateTime).Year - y
        End If
        If x = y Then
            Return 0
        ElseIf x > y Then
            Return 1
        Else
            Return -1
        End If
    End Function
End Class
' Write the following code in the code behind of the form
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load      
    ' Enable grouping
    FpSpread1.AllowColumnMove = True
    FpSpread1.ActiveSheet.GroupBarInfo.Visible = True
    FpSpread1.ActiveSheet.AllowGroup = True
    ' Set test data
    FpSpread1.ActiveSheet.SetValue(0, 0, DateTime.Today)
    FpSpread1.ActiveSheet.SetValue(1, 0, DateTime.Today.AddYears(1))
    FpSpread1.ActiveSheet.SetValue(2, 0, DateTime.Today.AddYears(11))
End Sub
Private Sub FpSpread1_Grouping(sender As Object, e As GroupingEventArgs) Handles FpSpread1.Grouping
    Dim colIndex = e.SortInfo.Last().Index
    ' Generate custom group in first column
    If colIndex = 0 Then
        e.GroupComparer = New MyGroupComparer()
    End If
End Sub