Yes, it's possible to do what you need. Check out the optional userid and password parameters of Auth.Authenticate (http://foxweb.com/document/AuthObject.htm).
FoxWeb Support Team
Sent by G Barfield on 10/05/2011 09:52:34 AM:
Is it possible to automatically (programatically) log someone in (authenticate them) once they change their username and password so they won't have to login again?