Will we ever be able to add existing users to our account?

You can create sub accounts that are managed. You can use your account to create managed accounts for specific Linodes or domains.

@John Henry Eden:

You can create sub accounts that are managed. You can use your account to create managed accounts for specific Linodes or domains.

Yeah but that sucks because each account has to have a unique username/password then we have to set up 2fa again etc etc. If an account owner could just enter our username in a box with a list of permissions it'd make my life easier.