When calling API to update the party, which collections need to be populated?

I need to change the party associated with an IB instance in many instances.  I am calling csi_item_instance_pub.update_item_instance, and since all I need to do is change the party, I've only populated the instance record and the party record.  I'm getting a pretty cryptic error message:

x_msg_count is 1
x_return_status is E
error msg is: CSI
CSI_API_INVALID_OWNER_ACCT
N
PARTY_ID
686164

This doesn't tell me much.  How does one know which collections need to be populated when calling these APIs?  The API manual says a big nothing about how to call these guys.  I think it's obvious that when updating the party, you shouldn't have to populate, say, the extended attributes collection.  But how does one know which collections have to populated for which types of updates?