ePro - how to do an 'amount only' req and create multiple PO's from that req?

We'd like to do an Amount Only requisition and then cut multiple PO's from that requisition.  When we do this now, the system only lets us create one PO even if the PO amount is less than the full amount of the requisition.  For example, requisition #100 is for $1000 as amount only.  We'd like to create a PO for vendor A for $250, and a PO for vendor B for $100.  At time progresses we can then create a PO from the remaining amount of the requisition.

The intent is to use this for our project-level requisitions so we may have multiple vendors included as part of the project.  The requisition would go through the approval workflow process to receive all the necessary approvals prior to creating POs.