Let's start with a trivial case, US states. There are 50 of them. Let's say that you've got a dozen or so solutions that all use the same data. Can you have a common states database that is referred to by all those solutions that is not, itself, shared (and thus using up one of the 125 slots for sharing databases)?
The real world example I've got is US governments, of which there are approximately 90k, each of which will have a significant amount of data. There will also be other databases, such as a bureau of labor statistics database, a bureau of economic analysis database, etc. The solutions I actually want to share will all be using these databases. Must these databases (which I want to have available locally for speed and reliability reasons) be replicated across the multiple solutions that will be using the data?