You don't add employees under Managers. Users are grouped under a company.
Please read this post: viewtopic.php?f=8&t=1024
It explains different roles of users in EPESI.
It would be possible to assign employees to managers with some customization:
First you would need to add another field (non-mandatory) for a contact - this would be another user as a select.
Then via Advanced Permission System you would need to apply some rules - for example non-managers should not have access to edit this field.
Things could get very complicated as we do not assign task filtering by users who belong to some manager.
A better and simpler approach would be to create "divisions" or branches for your company. Install a module called "Parent Company" which will allow you to create a tree-like structure. You can find it in EPESI Store - Module Manger under CRM:
Then create a "company" record for each "division" with one manager per company and multiple employees. By default tasks, meetings, phone calls etc. will be shared among people within the same company. This functionality is already built into EPESI (multi-company setup).