Yes, the new account structure allows you to invite multiple users to a sub-account where all users share contacts, templates, and inbox. This makes security and auditing much easier. If a team member leaves, simply disable their user access without impacting any other users.
Under the required parent or sub-account, go to Settings > Users. Click New User and follow the instructions. The new user will receive an email invitation to create their profile and access the account.
Read this article for detailed instructions on user management