Private ReadOnly list_a As String = "a|b|c"

Private ReadOnly list_b1 As String = " "
Private ReadOnly list_b2 As String = "1|3|5"
Private ReadOnly list_b3 As String = "2|4|6|8"
Private ReadOnly list_b4 As String = "7|9"

Private Sub Form1_Load(sender As Object, e As EventArgs)
　　C1FlexGrid1.Styles.Add("Combo1")
　　C1FlexGrid1.Styles("Combo1").ComboList = list_a

　　C1FlexGrid1.Styles.Add("Combo2")
　　C1FlexGrid1.Styles("Combo2").ComboList = list_b1

　　C1FlexGrid1.Cols(1).Style = C1FlexGrid1.Styles("Combo1")
　　C1FlexGrid1.Cols(2).Style = C1FlexGrid1.Styles("Combo2")
End Sub

Private Sub C1FlexGrid1_BeforeEdit(sender As Object, e As C1.Win.C1FlexGrid.RowColEventArgs)
　　If e.Col = 2 Then
　　　　If IsNothing(C1FlexGrid1(e.Row, 1)) Then
　　　　　　C1FlexGrid1.Cols(2).Style.ComboList = list_b1
　　　　ElseIf C1FlexGrid1(e.Row, 1).ToString() = "a" Then
　　　　　　C1FlexGrid1.Cols(2).Style.ComboList = list_b2
　　　　ElseIf C1FlexGrid1(e.Row, 1).ToString() = "b" Then
　　　　　　C1FlexGrid1.Cols(2).Style.ComboList = list_b3
　　　　ElseIf C1FlexGrid1(e.Row, 1).ToString() = "c" Then
　　　　　　C1FlexGrid1.Cols(2).Style.ComboList = list_b4
　　　　End If
　　End If
End Sub

Private Sub C1FlexGrid1_CellChanged(sender As Object, e As C1.Win.C1FlexGrid.RowColEventArgs)
　　If e.Col = 1 Then
　　　　C1FlexGrid1(e.Row, 2) = Nothing
　　End If
End Sub

private readonly string list_a = "a|b|c";

private readonly string list_b1 = " ";
private readonly string list_b2 = "1|3|5";
private readonly string list_b3 = "2|4|6|8";
private readonly string list_b4 = "7|9";

private void Form1_Load(object sender, EventArgs e)
{
　　c1FlexGrid1.Styles.Add("Combo1");
　　c1FlexGrid1.Styles["Combo1"].ComboList = list_a;

　　c1FlexGrid1.Styles.Add("Combo2");
　　c1FlexGrid1.Styles["Combo2"].ComboList = list_b1;

　　c1FlexGrid1.Cols[1].Style = c1FlexGrid1.Styles["Combo1"];
　　c1FlexGrid1.Cols[2].Style = c1FlexGrid1.Styles["Combo2"];
}

private void c1FlexGrid1_BeforeEdit(object sender, C1.Win.C1FlexGrid.RowColEventArgs e)
{
　　if (e.Col == 2)
　　{
　　　　if (c1FlexGrid1[e.Row, 1] == null)
　　　　　　c1FlexGrid1.Cols[2].Style.ComboList = list_b1;
　　　　else if (c1FlexGrid1[e.Row, 1].ToString() == "a")
　　　　　　c1FlexGrid1.Cols[2].Style.ComboList = list_b2;
　　　　else if (c1FlexGrid1[e.Row, 1].ToString() == "b")
　　　　　　c1FlexGrid1.Cols[2].Style.ComboList = list_b3;
　　　　else if (c1FlexGrid1[e.Row, 1].ToString() == "c")
　　　　　　c1FlexGrid1.Cols[2].Style.ComboList = list_b4;
　　}
}

private void c1FlexGrid1_CellChanged(object sender, C1.Win.C1FlexGrid.RowColEventArgs e)
{
　　if (e.Col == 1)
　　{
　　　　c1FlexGrid1[e.Row, 2] = null;
　　}
}