on submit need to bind combobox

Hi ,

Have form with combobox and Add Button .Onclick of Add displaying popup and adding items to list .need to reload only that combobox instead of whole page ? 
Give the combo box a Name (or put it in a container with a Name) and do an Ajax refresh when closing the pop-up just on the combo box. I believe there is a Forge component on "How to use cascade drop-downs which does this, or something similar.