Below is the code that saves user input into local storage for form 2 on index.html. How do I save user input for form 3 and 4 on the same page?

For instance, form 2 (below) has fields called aboutSetupOne and setupSummaries. Form 3 has a field called aboutSetupTwo, which also should appear in form2's setupSummaries. How would I incorporate form3?

HTML Code:
            function html5StorageSupported()
            { "use strict";
                return ('localStorage' in window) && window['localStorage'] !== null;
            }


            function determineNumberStoredElements()
            { "use strict";
                return html5StorageSupported() ? localStorage.length : "Not Applicable";
            }


            function initialize()
            { "use strict";
                document.form2.supported.value = html5StorageSupported() ? "Yes!" : "No (:"; // summaries
                document.form2.numStored.value = determineNumberStoredElements();

    }
    
// save data into fields before moving to new page
            function persistData()
                { "use strict";
                
                        var aboutSetupOne = document.form2["aboutSetupOne"].value;
                        var storageIndex = "local.storage2.aboutSetupOne";
                        localStorage[storageIndex] = aboutSetupOne;
 
                    document.form2.numStored.value = determineNumberStoredElements();

                }
                        
// load data into fields when returning to app
			function loadData()
			{ "use strict";

				var setupSummariesString = '';
				var showSummary = false;
                
				setupSummariesString += "--SUMMARIES--\nSetup 1 Summary: ";
				if (localStorage["local.storage2.aboutSetupOne"] === undefined)
				{
					document.form2["aboutSetupOne"].value = '';
				}
				else
				{
					document.form2["aboutSetupOne"].value = localStorage["local.storage2.aboutSetupOne"];
					setupSummariesString += localStorage["local.storage2.aboutSetupOne"];
					showSummary = true;
				}
                           
// write to another field	
				if (showSummary === true)
				{
					document.form2["setupSummaries"].value = setupSummariesString;
				}
				else
				{
					document.form2["setupSummaries"].value = '';
				}
			}            
  
// Clear data from local storage and form fields.

            function clearData()
            { "use strict";
                if (html5StorageSupported())
                {
                    localStorage.clear();
                    document.form2["aboutSetupOne"].value = "";
                    document.form2["setupSummaries"].value = "";

                    document.form2.numStored.value = determineNumberStoredElements();
                }
            }