PO and AP integrated creates workload conflicts between dept.

Hi, I just join Sage City suggested by our Sage consulting firm.

We started to integrate PO and AP at beginning of this year, right away there is a conflict of workload shift from AP to PO or vise versa, buyers are used to open PO in the old system with different delivery dates in one PO, it's hard to make them change to Sage recommended one PO per delivery, which is more efficient for both AP and receiving dept.. When PO has multiple deliveries creates more work for AP to process invoices compare previously only enter invoice date, number and amount when both departments in different systems.  Anyone in Sage City has good solution for this issue to make balance workload for both parties. please give your suggestion. thank you.