How to do the equivalent of object.Parent.Grandparent.Field in Creator?

How to do the equivalent of object.Parent.Grandparent.Field in Creator?

I have a form with a parent form and I frequently want to access the parent form data from the UI. One concrete example is an Inventory report. The Inventory has a Product and the product has a classification. I would like to display inventory.Product.Classification in the Report. Is there a way to do this? Lookups only seem to allow displaying a field on the looked up form.