Open PO list without Sales Orders

I have a report which will provide all the Open POs. This Report is Getting info from EKKO , EKPO and EKAT tables and Checking "if eket-menge gt eket-wemng" for Open PO.
Problem :
Third Party Sales Order is raised. Then the PO is created via PO Requesition generated from the sales order. This PO that is raised appears in This Outstanding PO Report, which user don't want.
How can I filter these POs? Is there any Indication Filed for this Type?

  I don't think there is a field by which you can make the difference between standard purchase order and individual purchase order if you haven't configure another document type. But you can still find that those purchase orders are linked to a sales order by checking table VBFA where VBFA-VBELN=purchase order number

  I guess there is a way to eliminate such third party PO's as well . Depending upon the schedule line config. in SD's IMG the PR and subsequently the PO is created with a particular account assignment category (It is either C or E ) . In addition the item category of such PO's is S meaning hird party POs .
Try config. the PO list using the above to eliminate sales related POs.