Динамическая создание обработчиков событий

// Класс чекбокса.
public class MyCheckBox : CheckBox
{
    private readonly List<CheckBox> _childs = new List<CheckBox>();
 
    public void AddChild(CheckBox child)
    {
        _childs.Add(child);
    }
 
    protected override void OnCheckedChanged(EventArgs e)
    {
        foreach (CheckBox child in _childs)
            child.Checked = Checked;
 
        base.OnCheckedChanged(e);
    }
}

// Используем.
private void Form1_Load(object sender, EventArgs e)
{
    var cb1 = new MyCheckBox { Text = "Category", Left = 10, Top = 10 };
    Controls.Add(cb1);
 
    var cb2 = new MyCheckBox { Text = "Subcategory", Left = 20, Top = 30 };
    Controls.Add(cb2);
    cb1.AddChild(cb2);
 
    var cb3 = new MyCheckBox { Text = "Subcategory", Left = 20, Top = 50 };
    Controls.Add(cb3);
    cb1.AddChild(cb3);
}

private void Form1_Load(object sender, EventArgs e)
{
    var cb1 = new CheckBox { Text = "CheckBox1", Left = 10, Top = 10};
    cb1.CheckedChanged += (cb, args) => MessageBox.Show((cb as CheckBox).Checked ? "CheckBox 1 checked" : "CheckBox 1 unchecked");
    Controls.Add(cb1);
 
    var cb2 = new CheckBox { Text = "CheckBox2", Left = 10, Top = 30 };
    cb2.CheckedChanged += (cb, args) => MessageBox.Show((cb as CheckBox).Checked ? "CheckBox 2 checked" : "CheckBox 2 unchecked");
    Controls.Add(cb2);
}

static CheckBox CreateCheckbox(int id)
{
    var cb = new CheckBox {Text = string.Format("CheckBox {0}", id), Tag = id};
    cb.CheckedChanged += (sender, e) =>
        {
            var checkBox = (CheckBox) sender;
            MessageBox.Show(checkBox.Checked
                ? string.Format("CheckBox {0} checked", checkBox.Tag)
                : string.Format("CheckBox {0} unchecked", checkBox.Tag));
        };
    return cb;
}
 
private void Form1_Load(object sender, EventArgs e)
{
    var cb1 = CreateCheckbox(1);
    cb1.Left = 10;
    cb1.Top = 10;
    Controls.Add(cb1);
 
    var cb2 = CreateCheckbox(2);
    cb2.Left = 10;
    cb2.Top = 30;
    Controls.Add(cb2);
}

cb1.CheckedChanged -=(cb, args) => MessageBox.Show((cb as CheckBox).Checked ? "CheckBox 1 checked" : "CheckBox 1 unchecked");