Are remaining funds on Requisition returned to the budget if it is partial processed to a PO?

Summary:

Are remaining funds on Requisition returned to the budget if Requisition is partial processed to a Purchase Order?

Content (please ensure you mask any confidential information):

If a Requisition for $100/or 100 units is processed to a Purchase Order (PO) for only $60/or 60 units, will the remaining $10/or 10 units on the requisition be automatically returned to the budget?

Provided that 25B does not support splitting the Requisition line to $60 and $40 when process it to a Purchase Order, therefore we have to select the whole Requisition line of $100, and later update the PO line to $60/or 60 units.

After PO is approved, Requisition is in 'Ordered' status and we cannot create any PO for the remaining $40.