Managing pages and blocks can be a lot of work. Integrated is multisite and likes to create loads of websites. To support this a parent - child structure for websites would save a lot of work.
On the website configuration form, add an option to choose a parent website. This should contain all other websites + an option "None". Option "None" is the default
When a page url is requested which is not available on the active website, the parent website must be consulted. When the parent website contains the page this page should be rendered
At this moment parent pages don't need to be visible in the overview at /admin/page/. This will be done in a later release