You’re using an earlier version of the Lookup connector here - in the latest release of the Lookup connector from the 23.3 release of CData Arc at https://arc.cdata.com/support/builds/ you’ll find that the Lookup feature has been revamped, and you can declare a parent folder for the new elements to be added to:

This even has a test button that you can use to try it out:

The version that you’re on is a little simpler, just allowing you to output a sibling element, so /Items/tracking_events/parcel_barcode should have worked - what were you seeing when you did that? 

Okay, I think I have more info on 23.0.8517.0

• Using a destination of /Items/parcel_barcode works. A new node is created
• /Items/thing/parcel_barcode did not create a new node ‘thing’ or subnode parcel_barcode. thing doesn’t exist in the original XML.
• /Items/tracking_events/parcel_barcode gives a ‘Success’ result but the parcel_barcode node is not added to the existing /Items/tracking_events.

In the meantime we  will upgrade to the latest version