With company id + user email, the sign in logic will fail. Right now user can sign in with email as its unique.

I have a product that offers a small lead management system. The architecture of product is simple so far. I have tables called 'companies', 'users', 'leads'. Users within a company have CRUD rights on leads. Now companies want their agents to have rights to operate leads. So we can ask companies to add their agent as a user within the company but there is a problem. Each user needs to have a unique email to register. So if one agent serves 5 companies they can't be added as a user by each of them. What should be the ideal way to handle this. Thought of having separate database for each company so that problem of unique email is resolved but I'm not sure how to manage multiple databases for updates