How can I look up purchase orders (sent to my vendors) that were related to an invoice?

I am running QB Desktop Premier: Manufacturing & Wholesale Edition (trial version)

To give a background of my application, we are a Manufacture/job shop that creates multiple different custom tools & products at the request of my customers.

For example; a customer may order a tool that requires me to order material from one supplier, send to a machine shop for machining, then send out for Heat treat, then we get the part back to finish grind precise details (cutting edges), before we finally sell it to the customer.

If the customer orders this same tool again 2 years from now I would like to be able to look up the past invoice to see what suppliers (POs) were involved in the project. Is this possible?? When I open an old invoice, it shows me the old Sales (Work) Order that generated the invoice, but it does not show what POs were related to this job (my POs sent to suppliers, not the customer's PO which shows on the invoice & sales order)

1) Quote generates Sales (work) Order

2) Purchase orders are created from the Sales Order via the 'Create Purchase Order' button (these POs list which sales order they relate to)

3) POs are received against

4) Sales order generates Invoice

From the sales order screen (while it is still open nor when it is closed) I cannot look up what POs are associated with it.

Thank you for your help!

(this is one of the reasons I want to switch from Sage50 to QuickBooks as your integration of POs is much better, but I cannot find how to do this which is one of the main things I need with POs)