With two comboboxes; How to load child item collections in second combobox based on the first combobox selected item

I'm working on a win project and I know this would be easy in WPF but I do not have the liberty to switch this project. I have to comboboxes, basically a Order ComboBox and an OrderItem ComboBox. I am using Entity Framework and I just wanted to find out what the best way would be to load the orderitems based on the order combobox selected order, i.e. each time an order is selected, the child combo must re开发者_开发百科fresh its collection to the relevant selected order. I am using DevExpress as my control suite and would also love a DevExpress LookupEdit control example and also perhaps a way of doing this in the grid control's repository lookup edit. Please help>>>>

There is an example showing how this can be done at:

How to filter a second LookUp column based on a first LookUp column's value