How to LiveBind TXMLDocument with TComboEdit in different Units?

I use Delphi since second version. It's the first time I'm going to try LiveBindings so I'm going to need a little push in there.

First I pick some XML from a server/file and put it to TXMLDocument. This XML has <Product Classes> with <Product Promotions> inside. So I could manually insert these products to a TComboEdit and extract promotions to ther ComboEdit every time the user selects a different product.

So I understand that it is possible to do that automatically using LiveBindings. How can I do that using a XML component inside a TDataModule linking it to a Firemonkey Form with the ComboEdits?