how to add multiples children to the border?

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C#

WPF

i create dynamic border and i want to add coupe of children to it but it only allow one child element
how to add more then once?

       private void AddItem_Click(object sender, RoutedEventArgs e)
        {

            Canvas piCanv = new Canvas()
            {
                Width = 80,
                Height = 150
                


            };
            Label price = new Label()
            {
                Content = "Price:"
            };
            TextBox priceEdit = new TextBox()
            {
                Width=30
            };
            
            Border rect = new Border()
            {
                Width = 100,
                Height = 200,
                CornerRadius=new CornerRadius(15),
                BorderThickness=new Thickness(5, 10, 15, 20),
                Margin = new Thickness(5, 5, 5, 5),
                BorderBrush = Brushes.SlateBlue,
 // it allow me just one  child
                Child=piCanv, 
// here i want to enter more element how can i do it?
            
            };

            Warp.Children.Add(rect);
        }