How to just update "rendered" property in JSF - ajax

Question

I've got a list of documents and I need to update all at once.
I did something like this:
<ui:repeat id="r_list" value="#{tareaController.controlador.documentosIndexar}" var="documentos" >
where documentosIndexar is the list of documents. It displays all the documents and its properties fine.
I have two panelGrids, one with the viewer of the document and another one with its information.
At the bottom of the information there's the list of documents.
I need to fill the document's information then select another one without losing the previous one.
I'm trying to update the whole ui:repeat and it renders the next document and its information ok but the information of the previous one is lost.
I also tried doing:
<ui:repeat id="r_list">
<p:panelGrid id="pg_document" rendered="#{tareaController.controlador.documentoSeleccionado.id eq documentos.id}">
<---- Document components here ---->
<p:ajax event="rowSelect" update=":f_tarea:r_list:pg_document" listener="#{tareaController.controlador.reemplazarLista(tareaController.documentoSeleccionado)}"/>
</p:panelGrid>
</ui:repeat>
All my components, and well, my page is inside a form called f_tarea, which is from its template.
When I do the above I update that panelGrid from the list, but just that one, and the variable in the rendered condition changed, so all the panelGrid dissapear.
Basically, what I want to do is update JUST the rendered condition on all the panelGrids inside the ui:repeat, so one hides and another one is shown without losing the previous one's information.

Answer 1

Ok. Excuse me I'm a completly stupid.
I tried doing something I haven't done before: downloading the PrimeFaces manual. On the AjaxBehavior section there's the "process" one which process a component in partial request.
I fixed it just by doing:
<p:ajax event="rowSelect" process=":f_tarea:r_list:pg_documento" update=":f_tarea:pg_doc" listener="#{tareaController.controlador.reemplazarLista(tareaController.documentoSeleccionado)}"/>
I won't delete the question in case that it helps someone in the future.