I'm currently working on my first umbraco site using MVC.  I'm trying to convert the templates for my news listing and news article pages.  Usually I would have the article be a child of the listing page so they could share certain content areas.

I would normally have the following in my news listing template so I could overwrite the MainContent content with that of the individual article page.

<asp:content ContentPlaceHolderId="MainContent" runat="server">
  <asp:ContentPlaceHolder Id="MainContent" runat="server">
    <umbraco:Macro Alias="NewsArticleList" runat="server" />
  </asp:ContentPlaceHolder>
</asp:content>

I can't see how to do something like this using MVC however.  I have tried using IsSectionDefined to set the article list to be default content but it doesn't seem to work.

@if (IsSectionDefined("newsBody")) {
 @RenderSection("newsBody");
}
else { 
   @Umbraco.RenderMacro("NewsArticleList")
}

How do I specify default content to show if a child template doesn't have content for a section.