Hi Dileep,
In my experience, the only way to have mutiple approval is through an approval task. This task is in the task tab which is a component of a Supplier Workspace so you need to Activate a Supplier Workspace template and for that you need to use SIM module.
If you don`t have any Supplier Workspace template activated then the only management that you can do with this supplier is to approve/reject in one step (one approver).
I really recomend to use a Supplier Workspace in order to manage your suppliers.
