If I understand the "multiuser" option correctly it should
be possible
to use Kerberos credentials stored during login if sec=krb5 or sec=krb5i
is used. For NTLM there is pam_cifscreds which can be added to the PAM
configuration. You might have to add the 'forward_pass' to pam_sss.so in
the auth section as well to make sure pam_sss will put the password on
the PAM stack for other modules.
Thanks - that was the final piece of the magic. Thanks for all your assistance.