From Divinity Engine Wiki
- query GetInventoryOwner([in](ITEMGUID)_Item, [out](GUIDSTRING)_Owner)
Returns the inventory/container that holds _Item in _Owner.
- Success/Failure: Fails if _Item is not in anyone's inventory nor in a container.
- _Owner: The character or item in whose inventory the item currently resides.
- This call returns the outermost container. I.e., if a character has crate in their inventory, and the crate contains a pouch with the item, this call will return the character.