>the listitem of listbox3 will be refreshed to A1, A2, B1, B2, B3
>and if listitem of listbox2 is C
>the listitem of listbox3 will be refreshed to C1, C2, C3, C4, and etc.
>and if listitem of listbox2 is blank, listbox3 will be blank.
>
>How can I do that and is there any alternative?

Well, I'm not really following your question but it sounds like you need to add a column to your lists at the far right, out of view, and populate it with a flag of some sort when your lists are loaded.