How do I to change the property value for custom DataGridViewComboBoxCell

Hello Everybody.
I developed Multi-column ComboBox and I used the first item in it to use it as a button to add a new item to the ComboBox as needed, I named the linked property NewItemButtonCaption. Till now everything is okay, after that I used that Multi-column CoboBox to create custom DataGridView Column and I cloned the new property in the ComboBoxCell and ComboBoxColumn.

The problem is that when I create the Column in a DataGridView the NewItemButtonCaption doesn't work.

   public class MCCoboBoxCell : DataGridViewComboBoxCell
    {
        public override Type EditType => typeof(MCCBEditingControl);

        public override Type ValueType => base.ValueType;

        public MCCoboBoxCell() : base()
        {
        }

        public override void InitializeEditingControl(
            int rowIndex, object initialFormattedValue,
            DataGridViewCellStyle dataGridViewCellStyle)
        {
            base.InitializeEditingControl(
                rowIndex, initialFormattedValue, dataGridViewCellStyle);

            MCCBEditingControl ctl =
                DataGridView.EditingControl as MCCBEditingControl;

            ctl.NewButtonText = NewItemButtonCaption;
            ctl.DropDownStyle = ComboBoxStyle.DropDown;
        }

        public override object DefaultNewRowValue =>
            base.DefaultNewRowValue;

        private string _NewButtonText = string.Empty;


        [NotifyParentProperty(true)]
        public string NewItemButtonCaption
        {
            get
            {
               return _NewButtonText;
            }
            set
            {
                _NewButtonText = value;
            }
        }
 
        public override object Clone()
        {
            var clone = (MCCoboBoxCell)base.Clone();
            clone.NewItemButtonCaption = NewItemButtonCaption;

            return clone;
        }
    }

    public class MultiColumnComboBox : DataGridViewComboBoxColumn, 
        INotifyPropertyChanged
    {
        MCCoboBoxCell MCCoboBoxCell;
        public MultiColumnComboBox()
        {
            if (MCCoboBoxCell == null)
            {
                MCCoboBoxCell = new MCCoboBoxCell();
                this.CellTemplate = MCCoboBoxCell;
            }
        }

        private string _NewButtonText = string.Empty;

        [NotifyParentProperty(true)]
        public string NewItemButtonCaption
        {
            set
            {
                _NewButtonText = value;
                RaisePropertyChanged("NewItemButtonCaption");
            }
            get
            {
                return _NewButtonText;
            }
        }
        public event PropertyChangedEventHandler PropertyChanged;
        private void RaisePropertyChanged(
            [System.Runtime.CompilerServices.CallerMemberName]
            string caller = "NewItemButtonCaption")
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(caller));
            }
                MCCoboBoxCell.NewItemButtonCaption = NewItemButtonCaption;
                this.CellTemplate = MCCoboBoxCell;
        }

        public override object Clone()
        {
            var clone = (MCCoboBoxCell)base.CellTemplate;
            clone.NewItemButtonCaption = NewItemButtonCaption;

            return base.Clone();
        }

    }

class Form1 : Form
    {
        private DataGridView dataGridView1;
        private Custom_DataGridColumn.MultiColumnComboBox Column2;
        DataTable dataTable = new DataTable("Accounts");

        public Form1()
        {
            InitializeComponent();

            #region DataTable Info   
        }
       
        private void InitializeComponent()
        {
            this.dataGridView1 = new System.Windows.Forms.DataGridView();
            this.Column2 = new Custom_DataGridColumn.MultiColumnComboBox();
            // 
            // dataGridView1
            // 
            this.dataGridView1.ColumnHeadersHeightSizeMode = 
            this.dataGridView1.Columns.AddRange(new 
 System.Windows.Forms.DataGridViewColumn[] {
            this.Column2});
...
            // 
            // Column2
            // 
            this.Column2.HeaderText = "Column2";
            this.Column2.Name = "Column2";
            this.Column2.NewItemButtonCaption = "Add New Item";//Not working
            // 
            // Form1
            // 
       ...

        }
    }