AME configuration of approval hierachies for SSHR approvals

Gurus,

My client has an approval chain:

Employee > Supervisor > Head of Dept > Head of HR > CEO

This approval chain needs to be implemented for SSHR based transactions. Using the supervisor hierachy would normally work as transactions flow up to CEO, however, not via Head of HR unless the employee is in HR department.

Basically we need to insert Head of HR before CEO as a mandatory approver for all employees.

Regards,

Joe.