I have a custom button that renders a section into my page.
The button is only visible on the DETAIL (view) page, when I click on it I want it to go to my EDIT page adding the new section. And when it is saved, a checkbox will be changed to true with the new section showing as well.

1. Save new case
2. click on button
3. go back to edit page with new section showing
4. checkbox set to true
5. click on save
6. save case with new section included

MY CONTROLLER----
  public boolean RenderSection{get; set;}
   public Boolean showFields {get; set;}

   public TestController(ApexPages.StandardController controller) {
        RenderSection= false;
   }

  public pageReference ShowFields() {
        RenderSection= true;
        PageReference InputCase = new PageReference('/apex/GADCase?ID='+ApexPages.currentPage().getParameters().get('ID'));
        return InputCase.setRedirect(True);
        
   }



MY APEX PAGE---
<apex:page standardController="Case"  extensions="TestController">      
<apex:form >


<h1>Rerender Section</h1>


<apex:pageBlock >
    <apex:outputPanel id="thePanelWrapper">
        <apex:outputPanel rendered="{!RenderSection}">
             <apex:pageBlockSection columns="2" title="Ticket Fields">
                    <apex:inputField value="{!Case.Financial_Impact__c}"  />
                    <apex:inputcheckbox label="checkbox" value="{!Case.checkbox__c}"  disabled="true"/>

             </apex:pageBlockSection>
        </apex:outputPanel>
    </apex:outputPanel>
</apex:pageBlock>

<apex:commandButton action="{!ShowFields}" 
      rerender="thePanelWrapper"
      value="Submit" 
      onclick="alert('Are you sure you want to escalate to a ticket?');"/>

    
    
</apex:form>
</apex:page>