WPF TreeView HierarchicalDataTemplate - binding to object with different child collections

Question

I am trying to bind a collection to wpf TreeView control using data templates. Each item(Person) in the collection also contains two different collections(Cars,

Answer 1

CompositeCollection is a good answer, except you can't bind the child collections to the DataContext because it's not a Freezable. You can only bind them to resources. (See this question for more on that.) That makes it kind of hard to use in a HierarchicalDataTemplate, since the ItemsSource in one needs to bind to a property in the current context to be useful.

If you don't need change notification on the collections, you can easily implement a property in your view model, e.g.:

public IEnumerable