Custom branding and design artifacts are integral parts of any site. As developers create solution packages which are going to deliver branding artifacts to the site, those changes must be applied to the site in a traceable fashion so they can be reversed or backed up. Also, as your SharePoint site goes through a branding upgrade, the design artifacts must be applied on existing sites without much intrusion to site operation.
This recipe focuses on updating SharePoint managed theme references automatically by using PowerShell. Using this approach, you will be able to update any of your existing sites to use the new theme.
Ensure the site you are using for testing, in our casehttp://intranet.contoso.com, has several sub-sites created under it.
If the root site doesn't have sites created under it, create them manually using the SharePoint user interface, or follow the steps in the Provisioning site hierarchy during solution...