The image below shows key roles and how they are mapped to the organization structure.
Most roles can be split across multiple persons but some roles are unique.
The mapping shown here is only indicative and the reporting can be changed as per requirement, for example the Department Heads are actually responsible for workflows within a department and if in multi company setup the same department cuts across multiple companies then the Department Head might be reporting into MD. If the Departments are designed to reside within a company then Department Head should report into the CEO of the company.
The hierarchy within HR team is configurable and the roles of HR Manager and
HR Executive are the key roles which have access to most of the workflows.