You can enroll another member, but you don't have to. If you have one in mind, then you could save up for a bit. We don't know of any contests that give away shares at the moment, but @sneakyninja sponsors shares for authors that are highlighted in The Daily Sneak. There is a submission process for guest curators. If you highlighted one of their articles and your submission is published, they would get a share that way. (And you could use the SBD that guest curators earn to sponsor them, and then you and they would each get another share!)