Notes/Domino 6 and 7 Forum : Readers field

hi all
we r realy in confusion for a system which we r developing for a company which has follwing hirarchy
1. MD
2. Bussiness Unit Head for each of 7 Departments of the company.
3. Heads (there is one or more heads in each dept)
4. Normal employee (working under one or more heads of one or more depts)

We have to develop 4 applications in this system including employee directory,Appraisal,training requirement,Key Result area.In first 3 applications subordinate can't view his superiors record.everyone can view his subordinates record. A head can see only his own record + normal employees under him only.A bussiness Unit Head can view his own + employees + heads of his department.MD can view every ones record.this is for other 3 applications but In Key result Area application an empoyee sets his/her targets after viewing his/her immediate superior.So in only this application a juniour can see his just seniors record but not his superiors and in this applicaion after setting his/her targets record goes to his immediate senior and he can edit it.We r doing this with server groups but for this we have to make more than 50 groups every person is to be assigned one or more groups mannualy.Can we do it with any other method.if anyone has any idea about it please help us.we will be highly obliged.
thanks