Dynamically Populate MVRS based on Record Producer Variable Value

[ShivangiC]

My requirement is on populating a reference variable[reference to expense request table] 'Referral ticket' in record producer I want its related fields to auto-populate in record producer variables like start and end date of expense, title, cost center , sub-cost center etc and there are line items[another table] as a related list in expense request table, I want expense type and short description of it to auto populated as rows of multi row variable set in record producer.

I have written script include and catalog client script till populating the record producer variables. But how to populate MRVS with the line items info. This is my Script Include:- 

var response = {};

    var referralId = this.getParameter('sysparm_referral_id');

    if (!referralId) return JSON.stringify(response);

    var exp = new GlideRecord('x_merl4_expense_ma_expense_request');

    if (exp.get(referralId)) {

      response.start_date = exp.getValue('start_date_of_expense');

      response.end_date = exp.getValue('end_date_of_expense');

      response.title = exp.getValue('description');

      response.cost_center = exp.getValue('cost_center');

      response.sub_cost_center = exp.getValue('sub_cost_center');

      // Fetch related line items

      var lineItems = [];

      var li = new GlideRecord('x_merl4_expense_ma_line_of_items');

      li.addQuery('er_no', referralId);

      li.query();

      while (li.next()) {

        lineItems.push({

          expense_type: li.getValue('expense_type'),

          short_description: li.getValue('short_description')

        });

      }

      response.line_items = lineItems;

    }

    return JSON.stringify(response);

  },

Please help me with script to write for populating MRVS 

[ShivangiC]

And this my Catalog client script which is not auto populating MRVS:- 

// Call a GlideAjax script to get the values from the referenced record

        var ga = new GlideAjax('GetReferralTicketDetails');

        ga.addParam('sysparm_name', 'getDetails');

        ga.addParam('sysparm_referral_id', newValue);

        ga.getXMLAnswer(function(response) {

            var result = JSON.parse(response);

            if (!result) return;

            g_form.setValue('cost_center', result.cost_center);

            g_form.setValue('sub_cost_center', result.sub_cost_center);

            g_form.setValue('start_date_of_expense', result.start_date);

            g_form.setValue('end_date_of_expense', result.end_date);

            g_form.setReadOnly('cost_center', true);

            g_form.setReadOnly('sub_cost_center', true);

            g_form.setValue('title',result.title);

            //Populating MRVS  

            var mrvs = 'line_items_claim';

            var row=[];

        result.line_items.forEach(function(item) {

                row.push({

                    'expense_type':item.expense_type,

                    'short_description':item.short_description

                });

                // Push the new record to the MRVS

            g_form.addInfoMessage("Rows of MRVS -> "+JSON.stringify(row));

            g_form.setValue(mrvs, JSON.stringify(row));

            });

        });