Using Samba 3 on ubuntu for standalone server on ms network.

Situation - student home-dirs are in directory /home/students/class but I want members of staff group to be able to r-x student home-dirs for checking work and inhibiting undesirable content.

The problem is that if group access is set to staff then students cannot access their home-dirs, but if group access set to users or students, then staff cannot access students home-dirs.

Students cannot be made members of staff group as that would give them access to staff only information.

How do you get around this ?