chained collection_selects RJS

Hi there I´m trying to get working a bunch of chained collection selects

so it is like this
from 2 collection selects I replace 2 divs (just text) and generate 2 more collections selects depeneding on the results from the first 2, but then I need to generate to more collection selects, but it fails, since when the page is loaded the @collection to generete the collection_select is not net created (it comes from the past 2) collection selects, I´m kind of lost of how to solve this problem.
does anyone have a tip that could I borrow

I´m using rjs to update multiple divs and I´ve tried
       render :update do |page|
         page.replace_html 'apDiv5', @nfc[0].name
         page.replace_html 'apDiv9', @nfc[1].name
         page.replace 'apDiv11', :partial => 'ter', :collection => @nfc
       end

but apDiv11 does not work (i have tried replace and replace_html)

the _ter.html.erb has
<%= f.collection_select :key_word ..... %>

also I have tried
         page.replace_html 'apDiv10',
         ' <select id="perro_gato" name="perro[gato]"><option value="1">1</option>
           <option value="4">4</option></select>
         '
and it works but there has to be a better solution, and it doesnt solve me the problem of the later collection not existing when the page is loaded

thanks in advance