How does WPF Binding navigate relationships? -

I am trying to implement the master-extension relationship as follows:

  (Shown in the combo box) (shown in DataGrid). ----------- | | ------------ | | Customer | | Order | | ----------- | | ------------ | | ID | --- Customer OrderRelation --- | Customer ID | | Name | | Order id | | ... | | ... | | ----------- | | ------------ |   
 But I have a & lt; All Customers & gt; Items in the combobox, for which I need to see all the orders from all customers displayed in all the data grid of the details.  
 Here is a snippet of XML code:  
  & lt; ComboBox X: Name = "CustomerCombobox" ... ... & lt; ComboBox.ItemsSource & gt; & Lt; CompositeCollection & gt; & Lt; ComboBoxItem content = "{static resource nullCustomer}" /> & Lt ;! - I wrote my own class NullCustomer - & gt; & Lt; Collection archive collection = "{binding source = {static processing software client selection}}" /> & Lt; / CompositeCollection & gt; & Lt; /ComboBox.ItemsSource> & Lt; / ComboBox & gt; & Lt; DataGrade ItemSource = "{Binding ElementName = CustomerCombobox, Path = Selected ITEM. Customer Authorization}" ... & gt;   
 Now I have two questions:  
 
 
 How to get bindings in the datagrid  path = chosen item.CustomersOrdersRelation  When  customer order relation  is not  selected  selected ITAM  (which is a data preview view on runtime)   
 
 It's the easiest way to modify my own  NullCustomer  class so that when I & lt; All Customers & gt; Will I have the  Allorder Collection WeatherSource  displayed?     
 
  
 
 
 
 
 implements  data overview , which is possibly used by the binding system to obtain that property.  
 
 Along with this, it returns a property  CustomerArother Relation , which will be  composited compilation  for all orders of customers < Code> Archive Store