C#

class ExtendedUserControl : MyUserControl {
 // etc
}

public partial class PricePanelBase : UserControl
{
    public PricePanelBase()
    {
        InitializeComponent();
        InstallControls();
    }

    protected virtual void GetControls(ControlCollection Ctrls)
    {
    }

    private int InstallControls()
    {
        ControlCollection Ctrls = new ControlCollection(CPanel);

        GetControls(Ctrls);

        foreach (Control Ctrl in Ctrls)
            CPanel.Controls.Add(Ctrl);

        return Ctrls.Count;
    } ...

public partial class PricePanel : PricePanelBase
{
    public PricePanel()
    {
        InitializeComponent();
    }

    protected override void GetControls(ControlCollection Ctrls)
    {
        DataGridView GrdVw = new DataGridView();

        GrdVw.Name = "dataGridView1";
        GrdVw.Location = new Point(3, 35);
        GrdVw.Size = new Size(438, 146);

        Ctrls.Add(GrdVw);
    }...

for (int i = 0; i <= DataPitStop.Count - 1; i++)
{
    richTextBox2.Text += DataPitStop[i] + "\n";
}
DataPitStop = DataPitStop.Distinct().ToList();