Add Json to RestSharp POST request body in ASP.Net

Dear Sir

How to add a Json List inside a JSON Request Body

Please help me out how to call tripSheetEwbBills in this 

ConsolateEwayBill

Request Body :

{
  "fromPlace": "BANGALORE SOUTH",
  "fromState": "29",
  "vehicleNo": "PQR9876",
  "transMode": "1",
  "TransDocNo":null,
  "TransDocDate":null,
  "tripSheetEwbBills": [
    {       "ewbNo": 371002700828    },
    {       "ewbNo": 301002700830    },
    {       "ewbNo": 341002700832    }
]} 

Worked : 

    private void EwayBill_Extend(string EwayBillNo)
    {
        string keyid = "Bearer " + APIkey;
        string body = "";
        string RequestId = Session["User"].ToString() + System.DateTime.Now.ToString("ddmmyyyyhhmmss");
        var client = new RestClient("https://gspte.com/test/enriched/ewb/ewayapi?action=VEHEWB");
        var request = new RestRequest(Method.POST);
        request.AddHeader("Content-Type", "application/json");
        request.AddHeader("Accept", "*/*");
        request.AddHeader("Connection", "keep-alive");
        request.AddHeader("Accept-Encoding", "gzip, deflate, br");
        request.AddHeader("requestid", "" + RequestId + "");
        request.AddHeader("Authorization", "" + keyid + "");
        List<tripSheetEwbBills> EList = new List<tripSheetEwbBills>();
        EList.Add(new tripSheetEwbBills
        {

            ewbNo = EwayBillNo
        });
        ConsolateEwayBill EWayBillExtend = new ConsolateEwayBill()
        {
            fromPlace = txtFromPlace.Text.ToUpper(),
            fromState = txtStateNumber.Text,
            vehicleNo = ddlRegisNumber.SelectedValue.Split('>')[0].ToString().Trim(),
            transMode = "1",
            TransDocNo = null,
            TransDocDate = null,
            
        };
        
        body  = JsonConvert.SerializeObject(EWayBillExtend);
        request.AddParameter("application/json", body, ParameterType.RequestBody);
        IRestResponse response = client.Execute(request);
        string ms = response.Content;
        var Response = JsonConvert.DeserializeObject<root>(ms);
        txtEwayBillNo.Text = Response.result.cEwbNo.ToString();
        if (Response.success == true)
        {
            string ValidUp = Convert.ToDateTime(Response.result.cEwbDate.ToString()).ToString("dd-MMM-yyyy");
            str = "UPDATE CT_EWAY_BILL_TRANS SET CONS_EWAY_BILL_NO='" + txtEwayBillNo.Text + "',EWAY_BILL_EXTEND_UPTO='" + ValidUp + "', PART_B_GEN='Y',VEHICLE_NUMBER='" + ddlRegisNumber.SelectedValue.Split('>')[0].ToString().Trim() + "',LAST_UPD_USER='" + Session["User"].ToString() + "', " +
                  "LAST_UPD_DATE=sysdate WHERE DIV_CODE='" + Session["DivCode"].ToString() + "' AND EWAY_BILL_NO='" + EwayBillNo + "' ";
            oper.sqedit(str);
        }
        else
        {

        }
    }
    private class ConsolateEwayBill
    {
        public string fromPlace { get; set; }
        public string fromState { get; set; }
        public string vehicleNo { get; set; }
        public string transMode { get; set; }
        public string TransDocNo { get; set; }
        public string TransDocDate { get; set; }
        public List<tripSheetEwbBills> EwayBills { get; set; }
    }
    public class tripSheetEwbBills
    {
       public string ewbNo { get; set; }
    }