Question about sharing Activities in Enterprise Version

Question about sharing Activities in Enterprise Version


I have the Enterprise version and set up two groups of CRM users: 1. FOUNDERS and 2. ALL
Also I have set two roles: CEO and Manager. The CEO and another manager are in the FOUNDERS group. The rest are in the ALL group.

The need:
There are certain activities (tasks and events)  that only needs to be shared to the FOUNDERS group. All other activities should be shared by ALL. For example there are some activities that only founders are engaged in and some other activities when everyone is involved. These latter ones are managed by a project manager (PM).

The issue:

I tried to set the data sharing setting but I have discovered that the Sharing Rules for Tasks and Events are missing even though one could set the rules for all other tabs. Why?

I have also tried to address this issue via custom "views" under the activities tab by making it visible to the FOUNDERS group. The result is that one can see the other founder can only see the custom view header but none of the activities inside since the activities have CEO as the owner.

Question:
Why is it not possible to create sharing rules for tasks/events and when this is planned to be implemented (if at all)? How to address this issue via a work around in the interim?

Thanks
Ed