Hi,

You can use merge fields to dynamically provide page reference in pageName attribute of <apex:include> tag.

Upon selecting a filter value you should update the page reference for the included pages by passing the parameter values in the url string and rerender the panel in which you have included the other pages.

Apex controller:

public with Sharing class PracticeFilterClass{ 

// public List<SelectOption> Filter {get;set;}
 
public String SelectedFilter{get;set;}
public String SelectedRegion{get;set;}
public String SelectedCountry{get;set;}
public String SelectedStateProvince{get;set;}
public String SelectedCity{get;set;}
public String SelectedRole{get;set;}

public PageReference FilterHeaderPageURL { 
get{
 /*create page reference by passing the parameters in the url of the page and use the parameter values in the    controller of the page.*/ 
return new PageReference('/apex/FilterHeaderPage?yourVar=yourValue'); 
} 
set; 
} 
/*Create pagereference for all the pages for which you want to pass the vales dynamically*/
}

 VF Page:

<apex:page >
<!-- rerender the below panel upon changing the filter values from dropdowns -->
<apex:outputPanel id="included-pages">
<apex:include pageName="{!FilterHeaderPageURL}"/>
<apex:include pageName="{!MyDashboardInfoURL}"/>
<apex:include pageName="{!MyDashboardRow2}"/>
</apex:outputPanel>
</apex:page>

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