Reroute wf mails to a group of people for particular plant & wf template

I have come across a very complicated scenario in workflow .

Normally , when a person creates a Purchase requisition for a particular plant ( company code ) a workflow triggers and a mail goes to the approver for approving it .

In the new scenario , We want that when a user creates a PR for a particular plant , then the mail of approval must go to a particular person or a list of people rather than the PR creator .

In short ,

We need the workflow to re route the mails on the basis of plant and workflow template to a group of people .