To match a Requisition to a Purchase Order already in Draft please follow the below steps:
Create the Requisition and fill in the header information as usual, then in the Lines tab click on the Available button. This will bring up all available Purchase Orders waiting to be matched.
Double click on the lines you wish to match and click Submit.
If there is a Workflow in place, the Requisition may then go to Pending Authorisations.
Once this has been authorised, you will see that the Purchase Order will show that it’s linked to the Requestion.