PO Creation through Decision Wizard Need to unapprove the PO instead of Approve

We have built a PO approval Workflow other than the Epicor PO Approval work flow. Since the customer will be using the buyer workbench to create RFQs and receive responses and create PO from decision Wizard screen and while creating the PO the system automatically approves the PO order is there any BPM or code where I can prevent the PO getting approved and trigger my work flow.

Dear Experts, How to unproven the PO while created through Decision Wizard?