Custom script for Dynamic reports to name field

I want to change the reports_to_name field as the reporting person has changed.I want the field to be updated from today’s date i.e. 19/11/19 but the reports_to_name field before 19/11/19 should show the old person’s name.How do I do this?? Please help I am new to erpnext.
Below is the custom script for same:

frappe.ui.form.on("Employee", {

"year": function(frm) {
    frappe.model.with_doc("Calendar Year", frm.doc.year, function() {
        var tabletransfer = frappe.model.get_doc("Calendar Year", frm.doc.year);
        $.each(tabletransfer.c_dates, function(index, row){
            var d = frm.add_child("dsr_submitted");
	d.date = row.date;
	d.employee = cur_frm.doc.name;
	d.employee_name = cur_frm.doc.employee_name;
	d.report_to = cur_frm.doc.reports_to;
	d.reports_to_name = cur_frm.doc.reports_to_name;
            frm.refresh_field("c_dates");
        });
    });
}
});

frappe.ui.form.on("Employee", {

"holiday_year": function(frm) {
    frappe.model.with_doc("Calendar Year", frm.doc.holiday_year, function() {
        var tabletransfer = frappe.model.get_doc("Calendar Year", frm.doc.holiday_year);
        $.each(tabletransfer.c_dates, function(index, row){
            var d = frm.add_child("dsr_submitted");
	d.date = row.date;
	d.employee = cur_frm.doc.name;
	d.employee_name = cur_frm.doc.employee_name;
	d.report_to = cur_frm.doc.reports_to;
	d.reports_to_name = cur_frm.doc.reports_to_name;
	d.holiday = 1;
            frm.refresh_field("c_dates");
        });
    });
 }
});

frappe.ui.form.on("Employee", "pause_dsr",  function(frm){

if (cur_frm.doc.pause_dsr == "1")
{
	cur_frm.toggle_reqd("from_date", true);
	cur_frm.toggle_reqd("to_date", true);
}
});

frappe.ui.form.on("Employee", "validate",  function(frm){

if (cur_frm.doc.pause_dsr == "1"){
	var start = new Date(cur_frm.doc.from_date);
	var end = new Date(cur_frm.doc.to_date);
	while (start <= end) {
		for(var i = 0; i < cur_frm.doc.dsr_submitted.length; i++)
		{
			var dsr = new Date(cur_frm.doc.dsr_submitted[i].date);
			if(dsr.getTime() === start.getTime())
			{
				cur_frm.doc.dsr_submitted[i].dsr_pause = 1;
			}
		}
		start.setDate(start.getDate() + 1);
	}
}
});

frappe.ui.form.on("Employee","reports_to", function()
{

for (var i =0; i < cur_frm.doc.dsr_submitted.length; i++){
cur_frm.doc.dsr_submitted[i].report_to = cur_frm.doc.reports_to;
}
      cur_frm.refresh_field('dsr_submitted')
});

 frappe.ui.form.on("Employee","reports_to", function()
{

 for (var i =0; i < cur_frm.doc.dsr_submitted.length; i++){
cur_frm.doc.dsr_submitted[i].reports_to_name = cur_frm.doc.reports_to_name;
}
cur_frm.refresh_field('dsr_submitted')
});

frappe.ui.form.on("Employee","status", function()
{

for (var i =0; i < cur_frm.doc.dsr_submitted.length; i++){
if(cur_frm.doc.status = 'Left')
{
cur_frm.doc.dsr_submitted[i].deactivated = 1;
}
}
cur_frm.refresh_field('dsr_submitted')
});

code does not look nice to read, please format it so some one can read atleast

How do I fetch the new “reports_to_name” from 19/11/2019 keeping old name “reports_to_name” i.e. before 19/11/2019.The “reports_to_name”(manager ) has changed from 19/11/2019.What line should I add?? Please help.