How to release Purchase Orders from an ASCP Plan that consolidated different Operating Units

Hi

We have three different Operating Units and we need to created an ASCP Plan that allow us to view the consolidated demands (itmes to buy) to negociate prices like only one company, but we need to release Purchase Orders for each Operating Unit. It's a cost issue. How can we do this?

We have two options for ASCP Plan: build the plan in an existing Operating Unit or in a new virtual operating unit. How to release Purchase orders keeping it’s source (Operating Unit that need it)?

Thanks  so much.