GridView Doesn't Contain Control Added In OnRowDataBound?

I can't get control which I added in DataGrid. I am adding it in OnRowDataBound event like:

protected void RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowState == DataControlRowState.Edit || e.Row.RowState == (DataControlRowState.Alternate | DataControlRowState.Edit))

//int cindex = 0;
//for (cindex = 0; cindex < e.Row.Controls.Count; cindex++)
foreach (Control ctl in e.Row.Controls)
{
DataControlFieldCell dcctl = (DataControlFieldCell)ctl;
TableCell tcell = (TableCell)dcctl;
Label lblComment = new Label();
TextBox txtComment = new TextBox();
lblComment.Text = "<br>Comment: ";
dcctl.Controls.Add(lblComment);
dcctl.Controls.Add(txtComment);
//tcell.Controls.Add(lblComment);
//tcell.Controls.Add(txtComment);
//e.Row.Cells[cindex].Controls.Add(lblComment);
//e.Row.Cells[cindex].Controls.Add(txtComment);

What is happening here: there is already exist one TextBox in TableCell by default and I want to add another one TextBox and Label. After the bounding I can see 2 textboxes, I can input data into the both, but when I click Update button, then raises OnRowUpdating event where I can't get my TextBox!

protected void RowUpdating(object sender, GridViewUpdateEventArgs e)
{
grdView.EditIndex = -1;
int counter = 0;
for (counter = 0; counter < grdView.Rows[e.RowIndex].Cells.Count; counter++)
{
foreach (Control ctl in grdView.Rows[e.RowIndex].Cells[counter].Controls)
{

And here I will be getting only default one TextBox (with its value). But my TextBox is disappeared! :(

P.S. I can't use predifined columns, like asp:TemplateField in aspx file, because my table has different amount of rows every time. It is dynamic