There are lots of different complexities with intercompany trade, depending on how you are organized internally, the geographic spread, boarders, types of goods nature of products etc. This video gives a run through of some of the basic setup.
Cheers
Lachlan
OrganicAX 
Is it possible to have an approval for PO confirmation. I have created a workflow, however POs’ with intercompany vendors cannot be submitted for workflows.
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Hi Ahmed
The purchase workflow is triggered with the change management setup in AP parameters and on the vendor master with optional override on the PO. So if you intercompany supplier has the change management turned on then the PO workflow will trigger.
This post might help.
https://organicax.com/2016/03/17/change-control-on-purchase-orders/
Cheers
Lachlan
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