Need Help with Multi-level Organization ACL Permission

[ivykong]

I am building a site for a university which will need to use multi-level ACL. This is similar to the case in NZ Green Party,

• Staff at university Provost's office has access to all faculty or students contact records,
• College dean has access to all faculty or students contact records within its college,
• Department chair has access to all faculty or students records within its own department.

I am trying to follow the instruction on this page about multi-level organization ACL permission  at wiki.civicrm.org/confluence/display/CRMDOC41/Multi-level+Organization+ACL+Permissions, and the post about permission hooks at  wiki.civicrm.org/confluence/display/CRMDOC41/CiviCRM+hook+specification#CiviCRMhookspecification-Permissionrelatedhooks.

However, before I come to the point to create a hook, the system doesn't allow me to use the the same field names in different custom field groups. I can't use the same fields (college, department) for the region and permissions group of custom fields.  Therefore, I assume the codes from the hook_civicrm_aclWhereClause won't work...

Anybody has suggestion how to make this work?

Thanks.