user_name_entry_field
password
company_login_name

gets posted to itself (index.php) which includes the session file (includes/session.inc) that checks if a session exists and if not, includes the  login form (access/login.php).

It is in the last file referred to above that you will need to create a secondary hook for your dual authorisation using a special unique session variable as a flag.

This will work if I want to capture second authentication at the same time as login.
In my case I would like to validate username+password first and only after that show separate captive page where I will handle additional auth (users can have different types MFA that will require different handling). Only after that second page user will be logged on. Failure at either of these steps will take user back to login.

I guess my question is "how can I introduce an additional page between successful login and taking user to the main application".

Is it possible to add one more step (with user interaction) to login process?
Have had a look at ldap_auth extension, but it seems to replace FA authenticate, where I want to add an extra step.

Thank you.