How to bind controls to multiple listboxes

I have a form tied to a database. There are two listboxes. One of them is bound to a binding source and is used to select the record that multiple textboxes are bound to. This works.
I want to use the other text box to also select the record that the textboxes are bound to.
The second list box is bound to another table that will allow records to be selected in the first table to be selected but I can not see how to control the current row in the binding source that the textboxes are bound to.