mysite/Layout2BasePage.php--
class Layout2BasePage extends Page {
	...
}

class Layout2BasePage_Controller extends Page_Controller {
	...
}

mysite/News2Page.php--
class News2Page extends Layout2BasePage {
	...
}
class News2Page_Controller extends Layout2BasePage_Controller {
	...
}

themefolder--
templates/
	Layout2BasePage.ss
	Page.ss
	templates/Layout/
		Page.ss
		News.ss
		Layout2BasePage.ss
		Layout2BasePageNews.ss