Hi, i can make it. You will need to have multiple API server (WPMU will also work), with a clean wp installation with available importable source. Different API server will be used so that you can make changes to appropriate sites, and that change is visible or importable. This would be the fair way, as different theme option, resources varies site to site. You can even use each API server as a demo/preview server.
On Your theme, we will use a custom module, or a plugin which will create an extra option page, and will guide to import data from any of the API servers.
Lastly, i can do it very well. Thanks.