Sourcing : How to create several PO for several UO from one negociation ?

Hi,
Consider a company with 3 sites :

Site 1 - Operation unit 1 : UO1
Site 2 - Operation unit 2 : UO2
Site 3 - Operation unit 3 : UO3



In Site 1, one enter a requistion # 1
In Site 1, one enter a requistion # 2
In Site 1, one enter a requistion # 3


In Sourcing, one enter a negociation from all the three requisitions, using UO1.

We would like to create 3 purchase order : one respectively for each UO.

PO1 for UO1
PO2 for UO2
PO3 for UO3

How to do it ?

Thank you in advance.
Regards.