The sharing arose out of the one consciousness to magnify joy by means of joint experience. That means there is nothing and no one that isn’t part of the sharing. You and everything that exists all make up the sharing together. No membership fee required. Everything and everyone share a divine nature, because they are all part of the sharing.
The book The Sharing: The Owner’s Manual for Being Human describes how the sharing is structured, how we as humans fit into that structure, and how we can use that knowledge to cocreate lives for ourselves that are happier, freer and more fulfilling.