As far as I am aware, the ability to set multiple passwords to join a private server does not exist.
My clan has and still does welcome new guests to play on our servers, so long as they register on our site first. We will literally give the password out to almost anyone who hasn't cause trouble before. The problem occurs when the very rare few who do break our rules, have the simple know-how to change their ip's and rejoin the server. Having to change the password to keep those players out; while keeping 40+ active clan members and dozens of guests in the loop, is an absolute pain.
It would just be great to be able to give clan members a password that will likely never change, and new guests a temporary password that will not affect the majority of our regulars if it needs to change.
U could use cl_privatepass but you would need to password every client by his name. Not good.
Or.
You make a script. On connection script to check if the client has a password cvar in his client info string. That way you could control almost all the players by password.
Ofc it is easier to say lol.