Fetch content from page in EPiServer CMS will basically get the properties from the target page and use them instead. This will only work if you don't have anything in each property. If you have a space in the MainBody for example, that property is not null and will therefore not be fetched from the other page. This works on a per property basis...

As long as you render properties based on the current page this will work great, using Html.PropertyFor or similar. If you have custom logic in view or controller it can sometimes mess up things. Hope that helps...

It won't matter where in structure you are. But some of those pages probably have properties that are not null (but maybe have a space or similar) and the Fetch content from page will then not work for that reason.

Happy coding!