If the PO is recurring, then all you really need is a Copy button for RMS Purchase Orders. This wouldn't need to be automated. Just locate the last PO, copy it, then immediately issue or receive it.
If you don't wish to wait for this feature to be added to RMS, try our Power Ops add-in which offers copy plus freight allocation or invoice discount prorated by dollars or units, carry forward partial PO's, and merge PO's. Power Ops also allows you to create a PO quickly with search and tag items, or quickly add new items while creating a PO.
Power Ops 30 day trial:
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(select Matrix Master or RMS Toolkit)
Greg Digital Retail Solutions
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(v1.x and 2.x compliant)
Try creating an Assembly.
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Works both ways, buyingand selling!