Creating Multiple Subforms

I am trying to add multiple subforms (or subtables?) on an existing form. The underlying table is a very detailed descriptive table for art in a collection, I am already using one subtable to manage the movement in and out of inventory. When I look at the table in the datasheet view, I see the "+" sign next to each record, and when I click on that, I see the subtable I already have setup - looking at that, it seems impossible to have more than one subtable... is this true? This does not seem right.

My question is this:
Can I have more than one subform in a given form? What I would like to have is a subform to keep track of provenance for any given piece (history of ownership), and another to track appraisals (values, dates, appraiser, etc) of any given piece in the collection.

Are there any samples of what I am trying to do?