How can I track and link POs for associated services?

Summary:

I have a case with my client where I need to track the purchase orders (POs) that have other associated services.

Example:

• A requisition for pipes is created.
• Pipes are purchased and a PO is issued.
• A freight service needs to be contracted from another supplier to transport those pipes.

Is there a way to link the freight PO with the pipes PO? And the freight PO with the requisition? If at the time of the request only the pipes are requested and not the freight, how is budget control managed in that case?

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