Shared content from one central point from the main MultiSite URL

I need to setup a MultiSite platform with cloned and branded sub sites (That's the easy part)
The bit that I don't know how to manage is that the sub sites need to be able to show the same Portfolio or post information that is on the main URL hub. This is so that universal changes are only made once on the hub and are updated across the MultiSite pages.

The second issue is that I also need to be able to switch some posts off or on in certain sub sites. Image attached: