2 Alternate states on One listbox?

[#1]

Hi Friends,

I have 2 listboxes: Study and Site.

I want only those sites to be shown under the selected study.

So i added the following expression to the site listbox :

aggr(only({<site_num= P(site_num)>}site_num),site_num)

It worked.

But 3 charts have to shown at study level and 5 on site level. So i created a 'study' alter nate state for the 3 charts and the study listbox. but now the site listbox is not getting affected by study listbox, as it is under inherited state(and so are the other 5 charts).

Can there be an expression for site listbox where it only picks up value of selected study from study loistbox, and not be a part of study alternate state?.

Thanks in advance.