I figured out how to set defaults for the multiple check boxes.
Here is my example:
DataTable tableMonths = new DataTable();tableMonths.Columns.Add("name", typeof(int));tableMonths.Columns.Add("value", typeof(string));tableMonths.Rows.Add(12, "12");tableMonths.Rows.Add(24, "24");tableMonths.Rows.Add(36, "36");tableMonths.Rows.Add(48, "48");tableMonths.Rows.Add(60, "60");tableMonths.Rows.Add(72, "72");RadComboBoxMonths.DataSource = tableMonths;RadComboBoxMonths.DataTextField = "name";RadComboBoxMonths.DataValueField = "value";RadComboBoxMonths.DataBind();// preselect these terms by defaultRadComboBoxMonths.SelectedValue = "12";RadComboBoxItem twelveMonths = (RadComboBoxItem)RadComboBoxMonths.SelectedItem;twelveMonths.Checked = true;RadComboBoxMonths.SelectedValue = "24";RadComboBoxItem twentyFourMonths = (RadComboBoxItem)RadComboBoxMonths.SelectedItem;twentyFourMonths.Checked = true;RadComboBoxMonths.SelectedValue = "36";RadComboBoxItem thritySixMonths = (RadComboBoxItem)RadComboBoxMonths.SelectedItem;thritySixMonths.Checked = true;