Shared albums with multiple photos libraries

I have 2 different photos libraries. One of them contains the scanned slides and pictures from my childhood, my parents' childhoods, and other ancestor pictures. The other library, which is my system library, has the pictures taken since I was married. My question is if I can create a shared album in a non-system library photos library. For instance, could I create a shared album of the favorites pics from my childhood that I could then access from my devices. Or, can I only do that from the main system library?

Thanks!