What "Partner" is used in the Reporting/Warehouse/Inventory Analysis?

• The partner in the Customer field on the Sales Order?
• The partner on the Internal Move?
• The partner in the Address field of the Location definition?

If I group the Inventory Analysis by Location + Partner, then I get more than one partner per location. It seems natural to me that a Location is in essence attached to only one Partner. What's going on here?

In particular, I have a product showing up in the correct location but the location is placed under the wrong partner. Some of the inventory at one location is under one partner and the remainder under another partner.