Requisition approval notification email

Hi,

We have been  using Position Employee-Supervisor hierarchy.  Where Hod generates Requisition and requisition goes to Senior Person and Once Senior person approves then it goes to final authority for approval.

Our business requirement is -  Hod creates Requisition email notification goes to Senior Person here we want only email notification should go to Hod Stores alongwith Senior Person.

What is the best solution to implement this?

Thanks

Gobind Ahuja