How do I transfer a Neon database from one Vercel org to another?

Basically the title. Someone has a Vercel organization on Neon with a couple databases. I've added him to my Vercel organization, which I assumed would make him a part of my Neon organization. But for him, my Vercel organization doesn't pop up on Neon. How can we do the transfer? According to Neon I manage organization members through Vercel.