SAP LSO Two Level Course Approval

I am using the following workflow for course approval in LSO:

Task           :WS12000003

Object type : LSO_PARTIC

Event          :BOOKREQUEST

This workflow working fine for one level approval.

My requirement is that there should be two level approval process, i.e, if Approver1 approve then this should go to another Approver2. If Approver2 approve then Course should be booked.

Please give me solution.

Regards

Ramji Dubey