How can I check/uncheck all checkboxes that are in a user control in a dropdownlist - C# Winforms

I created a user control to host some checkboxes that are created dynamically based on a list from a SQL table. I need to provide an option to select/unselect all checkboxes. This is easy to do when not created dynamically. The problem I find is that once I click on (ALL), yes, it will check or uncheck all checkboxes, but will not allow individual selection.

The code that generates the checkboxes is this:

 public void GenerateCheckboxesOnUserControl()
        {
            // Create user control.
            UserControl2 flp = new UserControl2();

            UserControl2 userControl2 = new UserControl2();
            userControl2.BorderStyle = BorderStyle.None;

            this.customComboBox4.DropDownControl = userControl2.flpanel;


            //*****************************//

            List<string> ItemList = new List<string>();

            ItemList.Add("Pending");
            ItemList.Add("New");
            ItemList.Add("Started");
            ItemList.Add("Declined");
            ItemList.Add("Completed");
            ItemList.Add("Accepted");
            ItemList.Add("Close");
            ItemList.Add("(ALL)");

            int i = ItemList.Count;

            CheckBox[] box = new CheckBox[i];
            _cbStatus = box;

            for (i = 0; i < ItemList.Count; i++)
            {

                box[i] = new CheckBox();
                box[i].Name = "cb" + ItemList[i].ToString();
                box[i].Tag = ItemList[i];
                box[i].Text = ItemList[i].ToString();
                box[i].Focus();

                box[i].BringToFront();
                box[i].CheckedChanged += new System.EventHandler(this._cbStatus_CheckedChanged);

                this.customComboBox4.DropDownControl.Controls.Add(box[i]);
                count++;

            }

            //****************************//
        }

The code that is used to check/uncheck is this:

public void _cbStatus_CheckedChanged(object sender, EventArgs e)
    {
        if (sender is CheckBox == false) return;

        UserControl2 userControl2 = new UserControl2();

        string message = string.Empty;
        string m = "";
        for (int i = 0; i < count; i++)
        {
            if (_cbStatus[i].Checked)
            {
                m += _cbStatus[i].Name + ", ";
                message += string.Format("boxes[{0}] is clicked\n ", i + " " + _cbStatus[i].Name);
            }

            foreach (Control cbStatus in customComboBox4.DropDownControl.Controls)
            {
                CheckBox cb = (CheckBox)cbStatus;
                if (cb.Name == "cb(ALL)" && cb.Checked)
                {

                    _cbStatus[i].Checked = true; 
                }
                else
                if (cb.Name == "cb(ALL)" && !cb.Checked)
                {

                    _cbStatus[i].Checked = false;
                }

            }

        }
        customComboBox4.Text = m;
        //MessageBox.Show(message);
    }

Obviously, if I remove the foreach loop, it will allow me to do individual selections. Any suggestion to make it work properly?

This is the codebehind for my user control:

private void InitializeComponent()
        {
            this.flpanel = new System.Windows.Forms.FlowLayoutPanel();
            this.SuspendLayout();
            // 
            // flpanel
            // 
            this.flpanel.AutoScroll = true;
            this.flpanel.Location = new System.Drawing.Point(4, 13);
            this.flpanel.Name = "flpanel";
            this.flpanel.Size = new System.Drawing.Size(215, 135);
            this.flpanel.TabIndex = 0;
            // 
            // UserControl2
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.BackColor = System.Drawing.SystemColors.ActiveCaption;
            this.Controls.Add(this.flpanel);
            this.Name = "UserControl2";
            this.Size = new System.Drawing.Size(222, 151);
            this.ResumeLayout(false);

        }

        #endregion

        public System.Windows.Forms.FlowLayoutPanel flpanel;
    }