I'm trying to markup page. I marked

WebPage 
   WPHeader
      SiteNavigationElement
   Bredcrumbs
   MainContentOfPage
     Article
        Product1
        Product2
   WPFooter

The question is: Should i aspire declare all internal entities of WebPage as "childs" of each other, or it's not necessary?

i.e.

WebPage (declared as "isPart" of WebSite)
   "hasPart" WPHeader
      "hasPart" SiteNavigationElement
   Bredcrumbs
   MainContentOfPage
     Article
        "about" Product1
        "about" Product2
   "hasPart" WPFooter

In first variant validator shows every entity as "top entity", an in the second variant validator shows only one top entity WebPage, and other entities included as WebPage properties,id's, e.t.c.

Which variant is better?