Repeater Control -- Adding another table row

I am trying to add some subtotals to a repeater control. Basically, repeater is bound to a dataset. Each record of the dataset creates a new table row. The subtotaler should detect when the date has changed in the data and insert a row. I am able to do this, but unfortunately it occurs AFTER the change, so the subtotal appears the row after the date has changed. I need it to occur before. I am using e.Item.Controls.Add to create this row dynamically in code. I have tried AddAt() with no success.

protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
        {
            // Customize each item based on data.
            if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
            {
                DataRowView row = e.Item.DataItem as DataRowView;
                if (DateTime.Parse(row["RecordDate"].ToString()) != lastdate)
                {
                    lastdate = DateTime.Parse(row["RecordDate"].ToString());
 
                    HtmlTableRow tr = new HtmlTableRow();
                    tr.BgColor = "FFFFD0";
 
                    HtmlTableCell tc = new HtmlTableCell();
                    tc.InnerText = "testing...";
                    HtmlTableCell tc2 = new HtmlTableCell();
                    tc2.InnerText = "more testing...";
                    tr.Cells.Add(tc);
                    tr.Cells.Add(tc2);
 
                    e.Item.Controls.Add(tr);
                    
                }
...

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