Invoice Approval in BPM for Purchase order with no supporting requisition

Summary

Invoice Approval in BPM for Purchase order with no supporting requisition

Content

We have a requirement as follows

currently we are able to route the BPM rule if invoice is not matched with a purchase order, should go for approval routing but if this is matched with a purchase order, invoice approval is not required and this is working absolutely fine

if Invoice is matched with a Purchase Order and if the purchase order has been sourced from requisition, the auto match condition should be approved, if the purchase order do not have purchasing requisition then this should go for approval.