Create Custom Control Of Nested Grid In WPF

While creating a custom control of nested grid i am not able to bind child grid. Can any body help me into it?

Below code is a custom control code

Code Below:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Collections;
using System.Windows.Controls.Primitives;
using System.Data;

namespace NestedCustomControl
{
    public class NestedGridControl : DataGrid
    {
        

        public override void BeginInit()
        {
            
            FrameworkElementFactory dtGrid = new FrameworkElementFactory(typeof(DataGrid));
            dtGrid.SetValue(DataGrid.ItemsSourceProperty, new Binding("setChildBind"));

            DataTemplate dttemp = new DataTemplate();
            dttemp.VisualTree = dtGrid;
           
            this.RowDetailsTemplate = dttemp; 

            base.BeginInit();
        }

        public BindingBase setChildBind
        {
            get
            {
                return (BindingBase)GetValue(SetChildBinding);
            }
            set
            {
                SetValue(SetChildBinding,value);
            }
        }

        

        public static readonly DependencyProperty SetChildBinding =
            DependencyProperty.Register("ChildBinding", typeof(BindingBase), 
            typeof(NestedGridControl), new FrameworkPropertyMetadata(OnChildGridSourceChange)); 

        private static void OnChildGridSourceChange(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
           

        }


        
        protected override void OnPreviewKeyDown(KeyEventArgs e)
        {
            DependencyObject dep = (DependencyObject)e.OriginalSource;

            //navigate up the tree
            while (dep != null && !(dep is DataGridCell) && !(dep is DataGridColumnHeader))
            {
                dep = VisualTreeHelper.GetParent(dep);
            }
            if (dep == null)
            {
                return;
            }

            DataGridCell dgc = dep as DataGridCell;

            if (dgc != null)
            {
                //navigate further up the tree
                while (dep != null && !(dep is DataGridRow))
                {
                    dep = VisualTreeHelper.GetParent(dep);
                }

                DataGridRow row = dep as DataGridRow;

                DataGrid dg = this as DataGrid;

                //row.Focusable = true;
                bool focused = row.Focus();
                FocusNavigationDirection focusDirection = FocusNavigationDirection.Down;
                FocusNavigationDirection focusDirectionUp = FocusNavigationDirection.Previous;
                TraversalRequest request = new TraversalRequest(focusDirection);
                TraversalRequest requestUp = new TraversalRequest(focusDirectionUp);
                UIElement elementWithFocus = Keyboard.FocusedElement as UIElement;

                if (e.Key == Key.Down)
                {
                    if (!e.Handled)
                    {
                        if (row.Background == Brushes.Gray && row.DetailsTemplate!=null)
                        {
                            row.DetailsVisibility = System.Windows.Visibility.Visible;
                        }
          
                        elementWithFocus.MoveFocus(request);

                        e.Handled = true;
                    }
                }
            }
        }
    }
}